Medical Encyclopedia B: Medical Terms Explained

B cells

White blood cells of the adaptive immune system that mature into plasma cells and produce antibodies after contact with a pathogen. Some become long-lived memory cells that react quickly on renewed contact.

B-Lynch suture

A compression suture around the uterus intended to stop bleeding mechanically in severe postpartum haemorrhage due to lack of uterine contraction. It can sometimes avoid hysterectomy.

B symptoms

The triad of fever above 38 °C, heavy night sweats and unintended weight loss of more than ten per cent in six months. It is especially significant in lymphomas and is included in staging.

Baastrup syndrome

Back pain caused by contact and friction between neighbouring spinous processes of the lumbar spine, usually in older people. The pain typically worsens when bending backwards.

Babesiosis

A tick-borne infection with single-celled parasites (Babesia) that invade red blood cells, similar to malaria. Severe courses mainly affect people without a spleen or with weakened immunity.

Babinski reflex

An abnormal reflex in which the big toe extends upwards after the sole of the foot is stroked. In adults it indicates damage to the pyramidal tract; in infants it is normal.

Babkin reflex

A newborn reflex in which pressure on both palms causes the mouth to open, the eyes to close and the head to bend. It is normal in the first months of life.

Baby blues

Temporary mood swings and tearfulness in the first days after giving birth that resolve on their own.

Bacillus anthracis

A spore-forming bacterium that causes anthrax. The highly resistant spores can survive in soil for decades and are taken up through the skin, airways or gut.

Bacillus cereus

A spore-forming bacterium frequently found in rice and pasta dishes kept warm too long after cooking. Its toxins cause vomiting or diarrhoea within a few hours.

Bacitracin

A polypeptide antibiotic against Gram-positive bacteria, used only externally, for example in wound and eye ointments, because of its kidney toxicity. It is often combined with neomycin; contact allergies are possible.

Baclofen

A muscle relaxant acting on GABA-B receptors in the spinal cord, used for spasticity, also via a pump directly into the cerebrospinal fluid. It must not be stopped abruptly, as dangerous withdrawal symptoms can occur.

Bacteraemia

The presence of bacteria in the blood, which can be temporary and harmless, for example after brushing the teeth. It becomes dangerous if it leads to sepsis.

Bacteria

Single-celled microorganisms without a nucleus. Most are harmless or useful, for example in the gut; some cause infections that can be treated with antibiotics.

Bacterial spores

Extremely resistant dormant forms of some bacteria, such as clostridia or Bacillus, that survive heat, drying and many disinfectants. They are reliably killed only by sterilisation.

Bacterial vaginosis

A disturbance of the vaginal flora with grey-white, fishy-smelling discharge.

Bactericidal

The property of an antibiotic or disinfectant to kill bacteria. Bactericidal agents such as beta-lactams are preferred in severe infections or weakened immunity.

Bacteriostatic

The property of an antibiotic to inhibit the multiplication of bacteria without killing them directly; the immune system then clears the organisms. Examples are tetracyclines and macrolides.

Bacteriuria

Detection of bacteria in the urine. Without symptoms it usually does not need treatment; exceptions include pregnancy or planned urological procedures.

Bacteroides fragilis

An anaerobic bacterium of the normal gut flora that can cause abscesses and peritonitis when the bowel is injured. It is typically treated with metronidazole or certain beta-lactam combinations.

Baden-Walker classification

An older, simple grading of genital prolapse into grades 0 to 4 according to the position of the lowest point relative to the hymen. It has largely been replaced by POP-Q.

Bado classification

A classification of Monteggia injuries into four types according to the direction in which the radial head is dislocated.

Bag-valve-mask ventilation

Ventilation with a self-inflating bag and a tightly fitted face mask. It is the basis of airway management in emergencies; an open airway and a tight mask seal are crucial.

Bagolini test

A test of binocular vision with finely striated lenses through which a light source appears as a streak. The arrangement of the perceived streaks reveals simultaneous vision, suppression or squint.

Bainbridge reflex

A circulatory reflex in which greater stretching of the atria from increased venous return raises the heart rate. It helps pump returning blood onward more quickly.

Baker classification

A grading of capsular contracture after breast implants into grades I to IV, from a soft, normal-looking breast to a hard, painful and deformed one. Capsular contracture is one of the most common long-term complications of breast implants.

Baker’s cyst

A fluid-filled bulge in the back of the knee, usually resulting from a knee joint disorder.

Bakri balloon

A balloon catheter inserted into the uterus and filled with fluid in heavy bleeding after birth to exert pressure from the inside. It bridges the time until bleeding stops or surgery.

Bakuchiol

A plant compound from the babchi plant marketed in cosmetics as an alternative to retinol. First small studies suggest similar effects with better tolerability, but the evidence is still limited.

Balanced anaesthesia

An anaesthetic technique combining an anaesthetic gas with intravenous opioids and, if needed, muscle relaxants. This allows each drug to be given at a lower dose.

Balanitis

Inflammation of the glans of the penis, often caused by fungi or bacteria and favoured by phimosis or diabetes. Redness, itching and burning are typical.

Balantidiasis

An intestinal infection with the ciliate Balantidium coli, transmitted mainly via pig faeces. It often goes unnoticed but can cause bloody diarrhoea similar to amoebic dysentery.

Bálint syndrome

A disorder of visual perception after damage to the parieto-occipital regions on both sides. Affected people can perceive only one object at a time, control eye movements poorly and have difficulty reaching for what they see.

Ballard score

An examination scheme for estimating a newborn’s gestational age from maturity signs of the skin and nervous system. It is helpful when the length of pregnancy is uncertain.

Baller-Gerold syndrome

A rare hereditary disease with premature closure of skull sutures and malformations on the radial side of the arm, such as an absent thumb. It is usually caused by mutations in the RECQL4 gene, which is also affected in Rothmund-Thomson syndrome.

Ballismus

Violent, flinging, involuntary movements of the arms or legs, usually one-sided as hemiballismus. The classic cause is a stroke in the region of the subthalamic nucleus.

Balloon enteroscopy

Endoscopic examination of the entire small intestine using one or two balloons that gradually thread the bowel onto the instrument. Unlike capsule endoscopy, it allows biopsies and treatment.

Balloon sinuplasty

A minimally invasive procedure in which a balloon catheter widens the drainage pathways of the sinuses. It is suitable only for selected forms of chronic or recurrent sinusitis without extensive polyps.

Balneophototherapy

A combination of a salt bath or a bath with a light-sensitising solution followed by UV irradiation. It is used mainly in psoriasis and atopic eczema.

Balneotherapy

Treatment with natural remedies such as thermal, brine or mud baths, usually as part of spa treatments. It is used as a complement, for example in rheumatic or skin diseases; the evidence varies by application.

Baloxavir

An influenza drug that inhibits the cap-dependent endonuclease of the influenza virus and is taken as a single dose. It should be given as early as possible, within 48 hours of symptom onset.

Balsalazide

A prodrug of mesalazine that is released by bacteria only in the colon. It is used in ulcerative colitis.

Balthazar score

A CT-based grading of acute pancreatitis into grades A to E which, together with the extent of necrosis, gives the CT severity index. It helps estimate severe courses.

Bamboo spine

An X-ray appearance of a spine whose vertebrae are continuously joined by bony bridges (syndesmophytes), resembling a bamboo stick. It is a late sign of advanced ankylosing spondylitis.

Bambuterol

A prodrug of the beta agonist terbutaline that can be given as a once-daily tablet for asthma. Today it is rarely used because of the advantages of inhaled preparations.

Band keratopathy

A band-shaped calcium deposit in the cornea in the area of the eyelid opening, for example in chronic uveitis or calcium metabolism disorders. It can be removed with a chelating agent.

Banff classification

An internationally agreed scheme for the histological assessment of biopsies from transplanted organs, especially the kidney. It distinguishes, among others, T-cell-mediated and antibody-mediated rejection.

Bankart lesion

Detachment of the front lower labrum of the shoulder socket, typically in an anterior shoulder dislocation. It favours repeated dislocations, especially in young, active people.

Bankart repair

Surgical reattachment of the torn labrum and capsule to the front rim of the shoulder socket, usually arthroscopically with suture anchors. It aims to prevent repeated dislocations after a Bankart lesion.

Bannayan-Riley-Ruvalcaba syndrome

A rare inherited disease of the PTEN hamartoma tumour syndrome group with a large head, pigmented spots on the penis, lipomas and bowel polyps. Because of the cancer risk, screening examinations are recommended.

BAP1 tumour predisposition syndrome

An inherited predisposition caused by mutations in the BAP1 gene, with an increased risk of choroidal melanoma, mesothelioma, renal cell carcinoma and skin melanoma. Affected people benefit from structured early detection programmes.

Bárány pointing test

A balance test in which the patient repeatedly points at the examiner’s finger with eyes closed. A sideways deviation can indicate a one-sided balance disorder.

Bardet-Biedl syndrome

A rare inherited ciliopathy with retinal degeneration, extra fingers or toes, obesity due to increased hunger, kidney changes and learning difficulties. The drug setmelanotide can be used against the hunger.

Bariatric surgery

Operations such as gastric bypass or sleeve gastrectomy for severe obesity.

Baricitinib

A JAK inhibitor tablet that blocks Janus kinases 1 and 2. It is used in rheumatoid arthritis, atopic eczema and alopecia areata; because of possible thrombosis, infections and cardiovascular events, risks must be weighed carefully.

Barlow test

A provocation test in infants in which the femoral head is pushed out of the socket by gentle pressure with the legs adducted. If this succeeds, the hip is unstable.

Baroreceptor

A pressure sensor in the wall of large arteries, for example in the aortic arch and carotid sinus, that registers changes in blood pressure. It allows rapid counter-regulation via the nervous system.

Baroreflex

A control loop in which pressure sensors in the carotid artery and aortic arch report changes in blood pressure and the nervous system immediately adjusts heart rate and vessel width. It prevents, for example, large drops in blood pressure on standing.

Barotrauma

Injury caused by pressure differences, for example when diving or flying, affecting mainly the middle ear and sinuses. Ear pain and reduced hearing are typical.

Barré arm drift test

A neurological test in which the arms are held outstretched with palms up and eyes closed. Slow drifting down and inward rotation of one arm suggests a mild central weakness.

Barrett’s oesophagus

Altered lining of the oesophagus due to long-standing reflux; it is considered a precancerous condition and is monitored regularly.

Barrier nursing

Nursing and hygiene measures intended to prevent transmission of pathogens, such as gowns, gloves and single rooms for multidrug-resistant organisms. It also serves to protect immunocompromised patients.

Barth syndrome

A rare X-linked disease in boys caused by mutations in the TAFAZZIN gene, which disrupts the structure of the mitochondrial membrane. Typical are heart muscle weakness, neutropenia, muscle weakness and growth delay.

Barthel index

A rating scale for independence in daily life, for example in eating, washing, walking or continence. It is used in geriatrics, nursing and rehabilitation.

Bartholin’s cyst

A fluid-filled swelling of a Bartholin’s gland at the vaginal opening caused by a blocked duct. If it becomes infected, a painful abscess develops that must be drained.

Bartholin’s gland

A pea-sized gland on each side of the vaginal opening that secretes lubricating fluid during sexual arousal. If its duct is blocked, a cyst or abscess can form.

Bartholinitis

Inflammation of the ducts of the Bartholin’s glands at the vaginal opening. If blocked, a painful abscess can develop that must be drained.

Barton fracture

A fracture of the radius at the wrist in which a rim fragment of the joint surface is displaced together with the carpus towards the back or palm of the hand. As an unstable joint fracture it is usually plated.

Bartonellosis

An umbrella term for infections with bacteria of the genus Bartonella. They include cat scratch disease, louse-borne trench fever and, in immunodeficiency, bacillary angiomatosis.

Bartsocas-Papas syndrome

A very rare autosomal recessive malformation with skin webs across the joints (pterygia), cleft lip and palate and malformations of the fingers and toes. It is caused by changes in the RIPK4 gene.

Bartter syndrome

A rare inherited disorder of salt reabsorption in the kidney with potassium and salt loss, low blood pressure and often growth problems in children.

Basal body temperature

The resting body temperature in the morning, which rises by about 0.2 to 0.5 degrees after ovulation due to progesterone. Measuring it is used to monitor the cycle; on its own it is unreliable as contraception.

Basal-bolus therapy

An insulin regimen in which a long-acting basal insulin covers basic needs and short-acting bolus insulin is injected with meals. It allows flexible mealtimes but requires regular blood sugar checks.

Basal cell carcinoma

The most common form of non-melanoma skin cancer. It grows slowly and hardly ever spreads, but should be removed early because it can grow into deeper tissue.

In depth: Basal Cell Carcinoma →

Basal cell layer

The lowest cell layer of the epidermis, in which skin cells continuously divide and melanocytes produce pigment. New skin cells arise from it and migrate to the surface in about four weeks.

Basal ganglia

A group of nuclei deep in the cerebrum that help control movement, drive and habit learning. Disorders of the basal ganglia underlie, for example, Parkinson’s disease and Huntington’s disease.

Basal insulin

Long-acting insulin that covers the body’s basic needs independently of meals for about a day or longer, for example insulin glargine or insulin degludec.

Basal stimulation

A care concept intended to give people with severely limited perception or communication orientation to their own body through targeted touch, movement and sensory stimuli. It is used, for example, in intensive care, neurology and care of people with dementia.

BASDAI

A six-question questionnaire with which patients self-assess disease activity in axial spondyloarthritis, for example fatigue, back and joint pain and morning stiffness. A score of 4 or more is considered high activity.

Base editing

A further development of CRISPR gene editing that specifically swaps single DNA building blocks without cutting the DNA double strand.

Base excess

A blood gas value indicating how much base is missing or in excess to normalise the pH. It helps classify metabolic acid-base disorders.

Basement membrane

A thin layer of collagen and other proteins beneath epithelia and around vessels that anchors tissue and acts as a filter. When a tumour breaks through it, the growth is called invasive.

Basic care

Regular moisturising skin care with emollients, the foundation of treatment for atopic eczema and dry skin.

Basic reproduction number

The average number of people an infected person infects in a fully susceptible population (R0). If it is above 1, an infection can spread; the vaccination coverage needed for herd immunity can be derived from it.

Basilar artery

The unpaired artery at the base of the brain, formed by the union of the two vertebral arteries, which supplies the brainstem, cerebellum and posterior parts of the cerebrum. Its occlusion (basilar thrombosis) is a severe emergency.

Basiliximab

A monoclonal antibody against the interleukin-2 receptor on T cells, given around kidney transplantation to prevent acute rejection.

Basket trial

A clinical trial that tests a drug in different tumour types carrying the same molecular change. It is typical of precision oncology.

Basophil activation test

A cellular allergy test in which basophils from the blood are brought into contact with the allergen in a test tube and their activation is measured by flow cytometry. It supplements skin and IgE tests in unclear cases.

Basophilia

An increased number of basophils in the blood. It is rare and can occur in allergies and underactive thyroid, but above all in chronic myeloid leukaemia, so it is investigated.

Basophilic stippling

Fine blue dots in red blood cells on a blood smear, consisting of RNA remnants. They occur, for example, in lead poisoning and thalassaemia.

Basophils

The rarest group of white blood cells, which store histamine and other messengers and are involved in allergic reactions. Raised counts can occur in certain bone marrow diseases.

Bateman classification

A classification of rotator cuff tears by tear size in centimetres from small to massive. It is used in reports and surgical planning.

Bath lift

An electrically operated seat that safely lowers people with limited mobility into the bathtub and raises them again.

Batten disease

An umbrella term for inherited neuronal ceroid lipofuscinoses, in which breakdown products accumulate in nerve cells. Typical are vision loss beginning in childhood, seizures and progressive mental and motor decline.

Battle sign

A bruise behind the ear over the mastoid process that usually appears only one to two days after an accident. It indicates a fracture of the skull base.

Baux index

A prognostic value in burns calculated as the sum of age and percentage of body surface burned. In the modified version, additional points are added for inhalation injury.

Baveno criteria

Consensus recommendations of the Baveno conferences (most recently Baveno VII) on portal hypertension, for example on risk assessment using liver stiffness and on the management of oesophageal varices.

Baxdrostat

A selective aldosterone synthase inhibitor that lowers aldosterone production and is being studied in difficult-to-control hypertension. A rise in potassium is a possible side effect.

Bayliss effect

The property of smooth vascular muscle to contract when internal pressure rises. This keeps blood flow to organs such as the kidney and brain constant over a wide range of blood pressures (autoregulation).

Bazedoxifene

A selective oestrogen receptor modulator (SERM) that acts like oestrogen on bone and blocks oestrogen in the uterus. It is used for postmenopausal osteoporosis and in combination with oestrogens.

Bazett formula

A formula for rate correction of the QT interval in which the measured QT is divided by the square root of the RR interval. At high heart rates it overestimates the corrected QT, at low rates it underestimates it.

BCLC staging

A staging system for liver cell cancer (Barcelona Clinic Liver Cancer, stages 0 and A to D) that links tumour burden, liver function and performance status with treatment recommendations.

BE-FAST

A mnemonic for recognising stroke: Balance, Eyes, Face, Arms, Speech and Time (call emergency services immediately). It extends the well-known FAST test with balance and visual disturbances.

Bearberry leaves (uva ursi)

A herbal remedy containing arbutin, used short-term for mild cystitis. Because of possible liver damage it is not suitable for long-term use.

Beau’s lines

Transverse grooves in the nails caused by a temporary growth disturbance, for example after severe illness, fever or chemotherapy. They grow out with the nail.

Beck Depression Inventory

A questionnaire with 21 groups of statements for self-assessment of depressive symptoms. It is used to determine severity and monitor progress.

Beck’s triad

The classic combination of signs of cardiac tamponade: low blood pressure, distended neck veins and muffled heart sounds. It is complete in only some patients; the diagnosis is confirmed by ultrasound.

Becker muscular dystrophy

An X-linked muscle disease caused by mutations in the dystrophin gene in which, unlike Duchenne, a shortened, partly functional dystrophin is still produced. It starts later and progresses more slowly.

Becker naevus

A large brownish patch, usually on the shoulder or chest, often with increased hair, that frequently becomes more noticeable during puberty. It is benign.

Beckwith-Wiedemann syndrome

A congenital overgrowth syndrome caused by imprinting changes in the chromosome region 11p15. Features include overgrowth, a large tongue, abdominal wall defects and an increased risk of childhood tumours such as Wilms tumour.

Beclometasone

An inhaled corticosteroid that, as a metered-dose inhaler or powder, dampens airway inflammation in asthma and COPD. It is also available as a nasal spray and is often combined with long-acting bronchodilators.

Bed bath

A complete wash of a bedridden person in bed, usually from top to bottom and from cleaner to less clean areas. The skin, pressure points and well-being are assessed at the same time.

Bed rails

A side rail on a care bed intended to prevent falls out of bed. If used against the person’s will, it counts as a restraint; low-floor beds are often an alternative.

Bedaquiline

A tuberculosis drug that inhibits the ATP synthase of mycobacteria and is a core component of treatment for multidrug-resistant tuberculosis. ECG monitoring is needed because of QT prolongation.

Bedbugs

Blood-sucking insects that hide in cracks in beds and furniture by day and bite at night. Itchy bites in rows are typical; professional pest control is usually needed.

Bedpan

A flat container placed under bedridden people for bowel movements or urination. A gentle technique protects the patient’s skin and the carer’s back.

Bedside test

A test of the recipient’s ABO blood group performed at the bedside just before a blood transfusion. It is intended to prevent dangerous mix-ups and is mandatory in Germany.

Beers criteria

A list from the USA of medicines that should be avoided or used with caution in older people. Like the German PRISCUS list, it helps prevent side effects.

Beger procedure

A duodenum-preserving resection of the pancreatic head in chronic pancreatitis, in which inflamed tissue is removed from the head of the pancreas while the duodenum and bile duct are preserved.

Beighton score

A nine-point score for assessing generalised joint hypermobility, for example overextension of the elbows and knees or palms flat on the floor with straight knees. From 5 points (in adults), generalised hypermobility is assumed.

Bejel

An endemic, non-sexually transmitted form of syphilis caused by Treponema pallidum endemicum, spread mainly among children in arid regions through skin and mucous membrane contact. The heart and nervous system are rarely affected.

Belantamab mafodotin

An antibody-drug conjugate against the surface molecule BCMA on myeloma cells that delivers a cell toxin directly into the tumour cell. It is used in previously treated multiple myeloma; corneal changes are an important side effect.

Belatacept

A fusion protein that blocks T-cell activation and is used to prevent rejection after kidney transplantation. Because of an increased lymphoma risk it is only for recipients with proven Epstein-Barr virus immunity.

Belimumab

An antibody against the B-cell growth factor BLyS (BAFF), used in addition to standard therapy in systemic lupus erythematosus and lupus nephritis.

Bell’s phenomenon

A protective reflex in which the eyeball rolls upwards when trying to close the eye. In facial palsy with incomplete eyelid closure, this upward rolling becomes visible.

Bell staging

A staging system for necrotising enterocolitis in newborns (I suspected, II confirmed, III advanced) based on clinical and radiological signs. It guides the decision between conservative and surgical treatment.

Bellocq tamponade

A posterior nasal pack for severe bleeding from the back of the nose in which a tampon is pulled through the mouth into the nasopharynx. Today balloon catheters are mostly used instead.

Belly button correction (umbilicoplasty)

A procedure to change the shape of the navel, often as part of a tummy tuck or for an umbilical hernia. Scars, infections and a result that does not meet expectations are possible.

Belly-press test

A shoulder test in which the hand presses against the abdomen while the elbow stays forward. If the elbow drops back, this suggests weakness or a tear of the subscapularis muscle.

Belzutifan

An inhibitor of the transcription factor HIF-2 alpha used for tumours associated with von Hippel-Lindau disease and in advanced renal cell carcinoma. Typical side effects are anaemia and low oxygen levels.

Bempedoic acid

A cholesterol-lowering drug that inhibits cholesterol production in the liver at an earlier step than statins. It is used mainly when statins are not tolerated or are insufficient alone, and hardly causes muscle complaints.

Benazepril

An ACE inhibitor for treating high blood pressure, also in combination with amlodipine. As with all ACE inhibitors, cough and rarely angioedema are possible.

Bence Jones protein

Free immunoglobulin light chains detectable in the urine. Their presence suggests a monoclonal plasma cell disease such as multiple myeloma, and they can damage the kidneys.

Bendamustine

An alkylating cytostatic used in chronic lymphocytic leukaemia, slow-growing lymphomas and multiple myeloma. It lowers lymphocytes for a long time, increasing the risk of infection.

Bendopnoea

Breathlessness occurring within a short time when bending forward, for example when tying shoelaces. It can indicate heart failure with raised filling pressures.

Benedikt syndrome

A brainstem syndrome caused by damage in the midbrain, combining oculomotor palsy on one side with tremor and movement disorders on the other side of the body. The most common cause is a stroke.

Benign

Not malignant. A benign tumour grows by displacing tissue but does not invade surrounding tissue or form metastases. The opposite is malignant.

Bennett fracture

An oblique fracture at the base of the first metacarpal involving the thumb’s saddle joint, with dislocation of the main fragment. Because it is unstable, it is usually fixed surgically.

Benperidol

A very high-potency butyrophenone antipsychotic related to haloperidol, used in acute psychotic states. Movement disorders are common.

Benralizumab

An antibody against the interleukin-5 receptor that leads to targeted depletion of eosinophils. It is injected every eight weeks as add-on therapy for severe eosinophilic asthma.

Benserazide

A dopa decarboxylase inhibitor combined in a fixed dose with levodopa. It prevents levodopa from being broken down outside the brain, so more reaches the brain and nausea is less common.

Bentall procedure

Heart surgery in which the aortic root and aortic valve are replaced by a vascular graft with a sewn-in valve and the coronary arteries are reimplanted. It is used, for example, for aneurysms of the aortic root.

Benzbromarone

A drug that increases uric acid excretion by the kidneys and is used in gout when allopurinol or febuxostat are unsuitable. Because of rare severe liver damage, liver tests are required.

Benznidazole

A drug against the pathogen of Chagas disease, Trypanosoma cruzi. It works best in the early phase of the disease; common side effects are rashes and nerve damage.

Benzocaine

A local anaesthetic used in lozenges and gels against pain of the skin and mucous membranes.

Benzodiazepine dependence

Physical and psychological dependence on benzodiazepines or Z-drugs, which can develop after a few weeks even at normal doses. Stopping abruptly can trigger seizures, so tapering is necessary.

Benzodiazepine overdose

An overdose of benzodiazepines with drowsiness, unsteadiness and slurred speech; it becomes dangerous mainly in combination with alcohol or opioids. Flumazenil is an antidote but is used cautiously because it can trigger seizures.

Benzodiazepines

Sedatives and sleeping pills that act quickly but can cause dependence after only a few weeks.

Benzoyl peroxide

An antibacterial active ingredient against acne; it can bleach fabrics and hair.

Benzyl benzoate

An active substance for external treatment of scabies, applied to the skin as an emulsion. It can burn and irritate and is an alternative when other agents are not tolerated or fail.

Benzylpenicillin

The classic penicillin (penicillin G), given intravenously or intramuscularly against streptococci, treponemes and other sensitive bacteria. It is destroyed by stomach acid and is therefore not effective as a tablet.

Bepirovirsen

An antisense oligonucleotide being studied in chronic hepatitis B; the aim is lasting disappearance of hepatitis B surface antigen from the blood.

Berlin definition

The definition of acute respiratory distress syndrome (ARDS) in use since 2012, with onset within one week, bilateral lung opacities not explained by heart failure and grading by the oxygenation index.

Bernard-Soulier syndrome

A rare inherited bleeding disorder in which the platelets lack a receptor (GPIb-IX-V) needed to adhere to von Willebrand factor. Characteristic are large platelets in reduced numbers and a prolonged bleeding time.

Berndt-Harty classification

A radiological classification of osteochondral lesions of the talus into stages I to IV, from compression to a loose fragment.

Berylliosis

A chronic lung disease from inhaled beryllium dust in which granulomas form, similar to sarcoidosis. It occurs occupationally, for example in the electronics or aerospace industries, and is recognised as an occupational disease.

BESD scale

An observation tool for assessing pain in people with dementia who can no longer report it reliably. Breathing, vocalisation, facial expression, body language and consolability are rated.

Best disease

An inherited macular dystrophy in which an egg-yolk-like yellow deposit forms beneath the centre of the retina. Vision often stays good for a long time and declines only later.

Best supportive care

The best possible supportive treatment without therapy directed at the tumour, focusing on symptom relief and quality of life. In studies it often serves as the comparison group.

Beta-2 microglobulin

A small protein found on almost all nucleated cells and excreted by the kidneys. Raised levels occur in impaired kidney function and lymphomas; in multiple myeloma it is used for staging.

Beta-alanine

An amino acid that contributes to forming the buffer carnosine in muscle and is used as a sports supplement. Harmless skin tingling is a common side effect; any performance benefit is limited to short, intense efforts.

Beta-amyloid

A protein fragment that is deposited as plaques between nerve cells in Alzheimer’s disease. It can be detected by cerebrospinal fluid testing or amyloid PET and is the target of new antibodies such as lecanemab and donanemab.

Beta-blocker poisoning

An overdose of beta blockers with slow pulse, low blood pressure and impaired consciousness. Besides atropine and catecholamines, glucagon and high-dose insulin with glucose are used.

Beta blockers

Medicines that dampen the effect of stress hormones on the heart. They lower pulse and blood pressure and are used for hypertension, heart failure, coronary heart disease and arrhythmias.

Beta cell

An insulin-producing cell in the islets of Langerhans of the pancreas that responds to rising blood sugar. Its destruction or exhaustion is central to type 1 and type 2 diabetes respectively.

Beta-CrossLaps (CTX)

Fragments of type I collagen released into the blood during bone breakdown. The value serves as a marker of bone resorption, for example to monitor osteoporosis treatment; it varies with the time of day and food intake.

Beta-D-glucan

A component of the cell wall of many fungi whose detection in the blood can indicate an invasive fungal infection. The test does not distinguish between fungal species and is usually negative for cryptococci and Mucorales.

Beta-hCG

A subunit of the pregnancy hormone hCG detected by pregnancy tests. Serial quantitative values help when ectopic pregnancy or miscarriage is suspected; it is also a tumour marker for germ cell tumours.

Beta-hydroxybutyrate

The most important ketone body in the blood, produced in greater amounts with insulin deficiency, fasting or alcohol excess. Measuring it in blood is more informative than urine tests when diabetic ketoacidosis is suspected.

Beta-lactamase

A bacterial enzyme that splits penicillins and related antibiotics and makes them ineffective. It is an important cause of antibiotic resistance.

Beta-lactamase inhibitors

Agents that block bacterial enzymes that destroy penicillins and related antibiotics. Combined with a beta-lactam antibiotic they widen its spectrum, for example tazobactam or clavulanic acid.

Beta-oxidation

The breakdown of fatty acids in the mitochondria, in which two-carbon units are cleaved off step by step as acetyl-CoA. It is a main energy source during fasting and endurance exercise.

Betahistine

A drug used in Ménière’s disease to reduce the frequency and severity of vertigo attacks. Its benefit is disputed in studies; more common side effects are gastrointestinal complaints and headache.

Betamethasone

A potent corticosteroid used as an ointment, tablet or injection. In obstetrics it promotes the baby’s lung maturation before an impending premature birth.

Betaxolol

A beta-1-selective beta blocker used as a tablet for high blood pressure and as eye drops for glaucoma. It is particularly long-acting.

Bethanechol

A direct parasympathomimetic that stimulates muscarinic receptors in the bladder and bowel and so promotes bladder emptying. It is used in non-obstructive urinary retention; side effects include sweating and diarrhoea.

Bethesda classification

A standardised reporting terminology for cytological smears, originally for the cervix and now also for thyroid aspirates. Each category is linked to a risk of malignancy and a recommended next step.

Betz cells

Very large nerve cells in the primary motor cortex whose long processes reach into the spinal cord. They are among the largest cells of the nervous system.

Bevacizumab

An antibody against the vascular growth factor VEGF that slows the formation of new tumour vessels. It is used in various cancers and in ophthalmology.

Bezafibrate

A fibrate that influences fat metabolism via PPAR-alpha and mainly lowers raised triglycerides. Muscle complaints are possible, especially in combination with statins.

Bezlotoxumab

A monoclonal antibody against toxin B of Clostridioides difficile, given in addition to antibiotics to reduce the risk of recurrence. The manufacturer discontinued it in 2025.

Bezoar

A compact lump of indigestible material such as hair, plant fibres or medicines in the gastrointestinal tract. It can cause fullness, ulcers or bowel obstruction.

Bezold-Jarisch reflex

A reflex in which stimulation of receptors in the left ventricle slows the heartbeat, widens vessels and lowers blood pressure. It can occur, for example, in inferior heart attack or severe volume depletion.

BI-RADS

A standardised reporting system for mammography, breast ultrasound and breast MRI with categories from 0 to 6. Each category indicates the likelihood of breast cancer and the next steps.

See also: Breast cancer

BIA-ALCL

Breast implant-associated anaplastic large cell lymphoma: a rare cancer observed mainly with textured-surface implants.

Bias

Systematic distortion of study results, for example through the selection of participants.

Bicalutamide

A non-steroidal antiandrogen that blocks the androgen receptor and is used in prostate cancer. Common side effects are breast tenderness and breast enlargement in men and hot flushes; liver values are monitored.

Bicarbonate

The most important buffer in the blood, which neutralises acids and is measured in blood gas analysis. Low levels suggest metabolic acidosis.

Bicarbonate buffer

The most important buffer system of the blood, made up of carbonic acid and bicarbonate, which neutralises acids and keeps the pH around 7.4. The lungs regulate carbon dioxide and the kidneys bicarbonate.

Biceps

The two-headed muscle of the upper arm that bends the elbow and rotates the forearm.

Biceps reflex

A tendon reflex in which a tap on the biceps tendon at the elbow causes the forearm to bend. It mainly tests the spinal cord segments C5 and C6.

Biceps tendon rupture

A tear of a biceps tendon, usually the long head at the shoulder. A bulge of the muscle on the upper arm, the so-called Popeye deformity, is typical.

Bickerstaff brainstem encephalitis

A rare immune-mediated inflammation of the brainstem with eye muscle paralysis, unsteadiness and impaired consciousness, often after an infection. It is closely related to Miller Fisher syndrome.

Bictegravir

An HIV drug from the integrase inhibitor group, taken once daily in a combination tablet with two other active substances. It has a high barrier to resistance.

Bietti crystalline dystrophy

A rare inherited retinal disease with glittering crystal deposits in the retina and sometimes the cornea. It leads to night blindness and progressive loss of vision.

Bifidobacterium

A genus of bacteria that particularly colonises the gut of breastfed infants and ferments lactose and dietary fibre. Certain strains are used as probiotics.

Bifonazole

An azole antifungal for athlete’s foot and other skin fungal infections, applied once daily. In combination with urea it is also used to detach fungus-infected nails.

Bigeminy

A rhythm in which every normal heartbeat is followed by an extrasystole, so the beats occur in pairs. It can be harmless but also occurs in heart disease or digitalis overdose.

Bilastine

A modern, non-sedating antihistamine for allergic rhinitis and hives. It should be taken on an empty stomach, as food and fruit juice markedly reduce absorption.

Bilateral vestibulopathy

Failure or marked weakness of the balance organs on both sides, for example after gentamicin treatment, in Ménière’s disease or without an obvious cause. Unsteadiness in the dark and blurred vision during movement are typical.

Bilirubin

A yellow breakdown product of the red blood pigment, excreted via the liver and bile. Raised levels cause jaundice.

Bilirubinuria

The presence of direct bilirubin in the urine, shown by a dark brown colour. It indicates bile congestion or liver cell damage, not increased breakdown of blood.

Billroth operation

The classic partial removal of the stomach: in Billroth I the remaining stomach is joined to the duodenum, in Billroth II to a loop of small intestine. Today it is performed mainly for tumours.

Bimatoprost

A prostaglandin analogue in eye drops that lowers intraocular pressure in glaucoma. Known side effects are red eyes, increased eyelash growth and permanent darkening of the iris; cosmetic use for eyelashes requires medical advice.

Bimaxillary orthognathic surgery

An operation in which the upper and lower jaws are cut at the same time and moved into a new position to correct marked jaw malalignment. It is usually combined with orthodontic treatment.

Bimekizumab

An antibody that blocks both interleukin-17A and -17F and is used in psoriasis and inflammatory joint diseases. Oral fungal infections are a typical side effect.

Binet staging

A staging system for chronic lymphocytic leukaemia into stages A, B and C based on the number of affected lymph node regions and on anaemia and low platelets. It helps with prognosis and treatment decisions.

Binge eating disorder

An eating disorder with recurrent binge-eating episodes without compensatory behaviour, often associated with shame and overweight.

Binimetinib

A MEK inhibitor used with encorafenib in advanced melanoma and lung cancer with a BRAF V600 mutation. Important side effects concern the eyes (serous retinal detachment), heart and skin.

Bioavailability

The proportion of an active substance that reaches the bloodstream unchanged and can therefore take effect.

Biobank

A collection of samples such as blood or tissue with associated data for research.

Bioelectrical impedance analysis

A method in which a weak current is passed through the body to estimate water, fat and muscle content. Results depend heavily on hydration, device and measurement conditions.

Bioequivalence

Equivalence of two medicines with the same active substance in terms of the amount and rate of absorption into the blood. For generics it is shown by comparing the area under the curve and peak concentration.

Biofeedback

A method in which body processes such as muscle tension, pulse or skin temperature are measured and made visible so that patients learn to influence them consciously. It is used, for example, for headaches and incontinence.

Biofilm

A slimy layer in which bacteria or fungi colonise surfaces such as teeth, catheters or implants. Organisms in biofilms are hard for antibiotics to reach.

Biographical work

A nursing and therapeutic method in which a person’s life story, habits and preferences are explored and included in their care. It is particularly important in supporting people with dementia.

Biohacking

Attempts to optimise the body and performance through self-experiments with diet, technology or supplements; many methods are not scientifically proven.

Biological age

A person’s age measured by physical characteristics rather than years lived; it is estimated, for example, using epigenetic clocks.

Biologics

Biotechnologically produced medicines such as antibodies or hormones, used for example in rheumatic disease, psoriasis or atopic eczema.

Biomarker

Measurable characteristics such as blood values, genes or imaging findings that indicate normal or disease processes or the response to treatment.

Bionator

A removable functional orthodontic appliance that guides tongue and lip function and is intended to influence lower jaw growth, for example in a retruded lower jaw.

Biophysical profile

An ultrasound-based assessment of the unborn baby according to Manning based on breathing movements, body movements, muscle tone, amniotic fluid volume and CTG. A low score indicates a possible risk to the baby.

Biopsy

Removal of a small tissue sample for examination under the microscope (histology). It is often decisive in confirming or ruling out cancer.

Biosimilar

A follow-on version of a biotechnologically produced medicine with demonstrated equivalent effect.

Biostimulators

Injectable substances such as poly-L-lactic acid or calcium hydroxylapatite intended to stimulate the body’s own collagen production.

Biot’s breathing

Irregular breathing in which several breaths of equal depth are interrupted by sudden pauses. It indicates damage to the respiratory centre, for example from raised intracranial pressure.

Biotin

Vitamin B7, important for skin and hair; deficiency is rare. High-dose biotin can distort laboratory values such as thyroid hormones.

Biotinidase deficiency

A congenital enzyme defect that disturbs the recycling of the vitamin biotin. Untreated, seizures and rashes can occur, but lifelong biotin prevents symptoms.

Biperiden

An anticholinergic used against movement disorders caused by neuroleptics, such as acute dystonia. In older people it can promote confusion.

Bipolar disorder

A mental illness with episodes of depression and episodes of abnormally elevated or irritable mood (mania). It is usually treated with mood-stabilising medicines and psychotherapy.

Birdshot chorioretinopathy

A rare chronic inflammation of the choroid and retina with cream-coloured spots resembling birdshot marks. It is strongly associated with the tissue marker HLA-A29.

Birt-Hogg-Dubé syndrome

An autosomal dominant disease caused by mutations in the FLCN gene, with small benign skin tumours on the face, lung cysts prone to pneumothorax and an increased risk of kidney cancer.

Bisacodyl

A stimulant laxative that stimulates bowel movement and draws water into the bowel. As a tablet it works after about 6–12 hours, as a suppository within an hour; long-term use without medical advice is not recommended.

BISAP score

A simple score for early estimation of the risk of death in acute pancreatitis within the first 24 hours. It considers urea, impaired consciousness, SIRS criteria, age over 60 and pleural effusion.

Bishop score

A score that rates the readiness of the cervix for birth based on dilation, length, consistency, position and the height of the baby’s head. It helps plan induction of labour.

Bismuth-Corlette classification

A classification of bile duct cancers at the liver hilum (Klatskin tumours) into types I to IV according to their extension into the hepatic ducts. It is used for surgical planning.

Bismuth subsalicylate

A bismuth compound containing salicylate, used for diarrhoea and indigestion and in combination therapies against Helicobacter pylori. A harmless but noticeable side effect is black discolouration of the tongue and stool.

Bisoprolol

A cardioselective beta blocker that lowers heart rate and blood pressure and is used in hypertension, coronary heart disease and heart failure. It should not be stopped abruptly.

Bispecific antibodies

Engineered antibodies with two different binding sites that, for example, grip a tumour cell and an immune cell at the same time. This allows the immune system to be directed specifically against cancer cells.

Bispectral index

A number between 0 and 100 calculated from the EEG that is intended to estimate depth of anaesthesia; values of about 40 to 60 are typical of general anaesthesia. It supplements but does not replace clinical judgement.

Bisphosphoglycerate (2,3-BPG)

2,3-bisphosphoglycerate is a metabolic product in red blood cells that reduces haemoglobin’s oxygen binding and so makes it easier to release oxygen to tissues. It rises, for example, at high altitude and in anaemia.

Bisphosphonates

Medicines that bind to bone and slow bone breakdown, especially in osteoporosis. Tablets are taken on an empty stomach with water while upright; jaw bone damage occurs rarely.

Bite raising

Increasing the vertical height of the bite with a splint, crowns or orthodontic measures, for example in severe tooth wear or a deep bite.

Bite registration

Recording the positional relationship of the upper and lower jaw so that dentures can be made to fit in the articulator. Wax, silicone or digital methods are used.

Bite wound

A wound from an animal or human bite that, despite a small skin opening, often goes deep and introduces germs from the oral flora. Cat and human bites become infected particularly often; besides wound care, tetanus protection and antibiotics may be needed.

Bitewing radiograph

A small X-ray in which the patient bites on a holder and the crowns of the back teeth of the upper and lower jaw are shown at the same time. It is particularly suitable for detecting caries between the teeth.

Bivalirudin

A direct thrombin inhibitor given by infusion, mainly during cardiac catheter procedures and in patients with heparin-induced thrombocytopenia. Its short half-life allows good control.

BK polyomavirus

A widespread virus that remains dormant in the kidneys for life after an unnoticed childhood infection. With strong immunosuppression, especially after kidney transplantation, it can cause nephropathy with graft loss.

Black classification

The classic classification of carious lesions and fillings into classes I to V according to their location on the tooth, such as pits and fissures, interproximal surfaces or the tooth neck. It is still used in teaching and documentation.

Bladder cancer

Cancer of the urinary bladder; the most important risk factor is smoking. A warning sign is painless blood in the urine.

Bladder exstrophy

A rare congenital malformation in which the bladder lies open on the abdominal wall because the front abdominal and bladder walls have not closed. It requires several operations in childhood to achieve continence and function.

Bladder training

A behavioural method in which the intervals between toilet visits are gradually lengthened to increase bladder capacity. It is used mainly for urge incontinence and overactive bladder.

Blalock-Taussig shunt

A surgically created connection between a systemic artery (usually via a vascular graft from the subclavian artery) and the pulmonary artery. In infancy it improves lung blood flow in certain cyanotic heart defects.

Bland-Altman plot

A graph for comparing two measurement methods: for each pair of measurements, the difference is plotted against the mean. This reveals systematic deviations and the limits of agreement, which a correlation coefficient does not show.

Bland-White-Garland syndrome

A rare congenital malformation in which the left coronary artery arises from the pulmonary artery. Infants develop a heart attack with restlessness and sweating during feeds; surgery is needed.

Blastic plasmacytoid dendritic cell neoplasm

A rare, aggressive blood cancer that usually begins with violet skin nodules and later affects the bone marrow and lymph nodes. Treatment options include tagraxofusp.

Blastocyst

An early embryonic stage about five to six days after fertilisation, a hollow sphere with an inner cell mass and an outer cell layer. At this stage the embryo implants in the uterine lining.

Blastocystis hominis

A common single-celled gut organism often found in people without symptoms. Whether and when it causes abdominal complaints is disputed; detection alone is usually not a reason for treatment.

Blastomycosis

A fungal infection with Blastomyces, found mainly in North America, which first affects the lungs via inhaled spores. It can spread to the skin, bones and other organs.

Blasts

Immature precursor cells of blood formation that normally occur only in the bone marrow. A raised proportion of blasts in blood or bone marrow is an important criterion for acute leukaemias.

Blau syndrome

A rare inherited granulomatous disease caused by mutations in the NOD2 gene, with the triad of rash, arthritis and uveitis, usually beginning before age five.

Bleeding time

A test in which the time until bleeding stops after a standardised skin incision is measured. It assesses primary haemostasis by platelets and vessels but has largely been replaced by modern platelet function tests.

Bleomycin

A cytotoxic antibiotic from Streptomyces bacteria that causes DNA strand breaks and hardly affects the bone marrow. It is part of the treatment of testicular cancer and Hodgkin lymphoma; lung damage is a feared side effect.

Blepharitis

Chronic inflammation of the eyelid margins with redness, scales or crusts on the lashes and burning eyes. Regular lid hygiene with warm compresses and gentle cleaning is the most important measure.

Blepharochalasis

A rare disease, mostly in young people, in which recurrent eyelid swelling leads to thin, slack eyelid skin. It must be distinguished from age-related dermatochalasis.

Blepharophimosis

A congenital narrowing of the eyelid opening in width, often combined with drooping upper lids and an epicanthus. It can be part of an inherited syndrome that also affects ovarian function.

Blepharoplasty

Eyelid surgery: an operation on the upper or lower lids in which excess skin and, if needed, fatty tissue are removed.

In depth: Eyelid Surgery →

Blepharospasm

A focal dystonia with involuntary, repeated squeezing shut of the eyelids that can lead to functional blindness. The standard treatment is botulinum toxin injections repeated every few months.

Blinatumomab

A bispecific antibody that binds simultaneously to CD19 on leukaemia cells and CD3 on T cells, bringing them together. It is used in acute lymphoblastic leukaemia; cytokine release syndrome and neurological side effects require monitoring.

Blister plaster

A special hydrocolloid plaster for blisters that cushions, reduces friction and supports healing in a moist environment.

Blood alcohol concentration

The proportion of alcohol in the blood, given in Germany mostly in per mille. Even low levels slow reactions; legal limits apply for driving, and high levels can be life-threatening.

Blood-brain barrier

A protective barrier between blood vessels and the brain that keeps out many substances and pathogens – but also some medicines.

Blood circulation

The system of heart and vessels. In the pulmonary circulation the blood is loaded with oxygen; in the systemic circulation it distributes oxygen and nutrients.

Blood clotting

The process by which platelets and clotting factors seal an injured vessel wall. Important laboratory values are PT/INR and aPTT.

Blood-CSF barrier

A barrier at the choroid plexus where tightly joined epithelial cells control which substances pass from the blood into the cerebrospinal fluid. A disturbance shows in CSF testing, for example as a raised albumin ratio.

Blood culture

A laboratory test in which blood is incubated in culture media to detect bacteria or fungi in the blood. It is central when sepsis is suspected and is taken before starting antibiotics.

Blood donation

Voluntary giving of blood for patients; red cells, plasma and platelets are usually obtained from one donation.

Blood doping

A banned method of enhancing performance by increasing the number of red blood cells through transfusion of one’s own or donor blood. It thickens the blood and increases the risk of thrombosis, stroke and heart attack.

Blood flow restriction training

Strength training with light weights in which a cuff partly restricts venous return from the arm or leg. It is used in rehabilitation; caution is needed in vascular or clotting disorders.

Blood gas analysis

Measurement of oxygen, carbon dioxide and acid-base balance in the blood, for example in intensive care.

Blood glucose meter

A device that determines the current blood sugar level from a drop of blood. It is indispensable for many people with diabetes.

Blood group

Inherited markers on red blood cells. The most important are the ABO system (A, B, AB, O) and the Rhesus factor; they determine the compatibility of blood transfusions.

Blood plasma

The liquid part of blood without blood cells; it contains water, proteins, salts, nutrients and hormones.

Blood pressure

The pressure of blood on the vessel walls, given in mmHg as an upper (systolic) and lower (diastolic) value. Values below 120/80 mmHg are considered optimal.

Blood pressure cuff

An inflatable cuff for measuring blood pressure at the upper arm or wrist. A cuff that is too small or too large distorts the values, so its size must match the arm circumference.

Blood pressure monitor

A device for measuring blood pressure at the upper arm or wrist. For reliable values, measure at rest, seated and with the right cuff size.

Blood smear

A drop of blood thinly spread and stained on a slide and examined under the microscope. It shows the shape and maturity of blood cells and, for example, malaria parasites.

Blood sugar

The concentration of glucose in the blood. In healthy people, fasting levels are below 100 mg/dl (5.6 mmol/l).

Bloom syndrome

An autosomal recessive disease caused by a defect in the DNA helicase BLM, leading to chromosomal instability. Affected people are short, sensitive to light with facial redness and have a greatly increased cancer risk from a young age.

Blount disease

A growth disorder on the inner side of the upper shin bone that leads to increasing bow legs. It occurs in toddlers or adolescents; obesity is a risk factor, and braces or surgery are used depending on severity.

Blow-out fracture

A fracture of the thin floor or inner wall of the eye socket from a blunt blow to the eye, for example from a ball or fist, while the eyeball itself usually remains uninjured. Double vision when looking up is typical.

Blue light protection

Protection against visible short-wave light, for example from tinted sunscreens containing iron oxide. Screen light plays hardly any role, but sunlight can worsen pigment disorders such as melasma.

Blue naevus

A benign mole with a blue to blue-grey colour caused by pigment cells in deeper skin layers. It is usually small, sharply defined and harmless but should be checked if it changes.

Blue rubber bleb naevus syndrome

A rare vascular malformation with numerous bluish, rubbery venous nodules in the skin and gastrointestinal tract. Bleeding from the bowel can lead to iron deficiency anaemia; sirolimus is used therapeutically.

Blue Zones

Regions with a remarkably high number of centenarians, such as Okinawa or Sardinia. Common features include plant-based diets, everyday physical activity and close social ties.

Blumberg sign (rebound tenderness)

Pain in the lower right abdomen on suddenly releasing pressure on the left abdominal wall. It is considered a sign of peritoneal irritation in appendicitis.

Blunted affect

Reduced emotional responsiveness in which facial expression, voice and gestures show little emotion. It occurs as a negative symptom in schizophrenia, but also in depression or as a side effect of medicines.

Bobath concept

A therapy and care concept for people with brain damage, for example after stroke, that specifically promotes everyday movements and perception.

Bocavirus

Human bocavirus, a parvovirus that can cause respiratory infections and wheezing, mainly in young children. It is often detected together with other viruses.

Body cell mass

The proportion of metabolically active body cells, mainly muscle and organ cells, in fat-free mass. It is usually estimated by bioelectrical impedance analysis and used to assess nutritional status.

Body mass index (BMI)

A measure of body weight relative to height: weight in kg divided by height in metres squared. 18.5–24.9 is considered normal weight; from 30 it is called obesity.

Body plethysmography

A lung function test in a closed cabin that measures total lung volume and airway resistance as well as airway obstruction. It depends less on patient effort than spirometry.

Boerhaave syndrome

A spontaneous rupture of all layers of the oesophageal wall, usually after violent vomiting. It is an emergency with severe chest or upper abdominal pain and a risk of mediastinitis.

Bohr effect

A physiological effect in which carbon dioxide and a falling pH weaken haemoglobin’s oxygen binding. As a result, the blood releases more oxygen precisely in working, metabolically active tissues.

Bolus insulin

Fast-acting insulin injected with meals or to correct high values, for example insulin aspart or insulin lispro.

Bolus obstruction (choking)

Acute airway obstruction from a swallowed piece of food, often in older people or those with swallowing disorders. Back blows between the shoulder blades and, if needed, abdominal thrusts can dislodge it.

Bombay blood group

A very rare blood group in which the base substance H is missing and therefore no A or B antigens are formed. Affected people may only receive blood from other Bombay donors.

Bone splitting

A technique for widening a narrow jaw ridge in which the bone is split lengthwise and spread apart to make room for implants.

Bonferroni correction

A simple method in multiple testing that divides the significance level by the number of tests to limit false-positive results. It is considered rather strict.

Bonwill triangle

An equilateral triangle with sides of about ten centimetres between the two condyles of the jaw and the contact point of the lower central incisors. The model serves as an average value for constructing dentures.

Booster vaccination

A repeat vaccination that restores protection after some years, for example every ten years against tetanus and diphtheria.

Borage oil

A seed oil rich in gamma-linolenic acid, used in skin care products and dietary supplements.

Borborygmi

Audible, gurgling bowel sounds caused by gas and fluid moving in the intestine. They are usually harmless but can be louder in diarrhoea, malabsorption or early bowel obstruction.

Borden classification

A classification of dural arteriovenous fistulas into types I to III according to venous drainage, in particular whether veins of the brain surface are involved. Fistulas with such drainage have a higher risk of bleeding.

Borderline personality disorder

A mental illness with intense emotional swings, unstable relationships and impulsive behaviour; well-studied psychotherapies help.

Bordetella pertussis

A Gram-negative bacterium that causes whooping cough. Its toxins paralyse the cilia of the airways and lead to weeks of coughing fits.

Boreout

A colloquial term for exhaustion caused by persistent under-challenge and meaninglessness at work. It is not a medical diagnosis but can be accompanied by depression.

Borg scale

A scale on which people rate their perceived physical exertion, classically from 6 to 20. It helps guide training intensity, for example in cardiac rehabilitation, without measuring the pulse.

Börjeson-Forssman-Lehmann syndrome

A very rare X-linked disease affecting mainly boys, with intellectual disability, obesity, underdeveloped gonads and typical facial features.

Borna virus encephalitis

A rare, usually fatal brain inflammation caused by Borna disease virus 1, which originates from bicoloured white-toothed shrews in parts of Bavaria and neighbouring regions. Human-to-human transmission has not been observed.

Bornaprine

An anticholinergic used mainly against excessive sweating and Parkinsonian tremor. Typical side effects are dry mouth, constipation and visual disturbances.

Bornholm disease

An infection usually caused by coxsackie B viruses, with sudden, stabbing muscle pain in the chest or upper abdomen that worsens with breathing, often with fever. It usually resolves within one to two weeks.

Borrelia burgdorferi

A spiral-shaped bacterium of the Borrelia burgdorferi complex, transmitted by tick bites, that causes Lyme disease. Several related species occur in Europe and preferentially affect different organs.

Borrmann classification

A macroscopic classification of advanced stomach cancers into four types from polypoid to diffusely infiltrating. Type IV corresponds to the picture of linitis plastica.

Bortezomib

The first approved proteasome inhibitor: it blocks protein breakdown in the cell, to which myeloma cells are particularly sensitive. It is a cornerstone of multiple myeloma treatment; painful polyneuropathy is common.

Bosentan

An endothelin receptor antagonist for pulmonary arterial hypertension. Monthly liver tests and reliable contraception are required.

Bosniak classification

A classification of kidney cysts on CT or MRI based on walls, septa and contrast enhancement. It estimates the risk of malignancy and determines whether follow-up or surgery is needed.

Boston Bowel Preparation Scale

A rating scale for bowel cleanliness during colonoscopy in which three bowel segments each receive 0 to 3 points. Good preparation is important so that polyps are not missed.

Bosutinib

A tyrosine kinase inhibitor against the BCR-ABL fusion protein used in chronic myeloid leukaemia. Diarrhoea in the first weeks of treatment and raised liver enzymes are common.

Botulinum toxin

A nerve toxin from the bacterium Clostridium botulinum that, in tiny amounts, blocks the transmission of nerve impulses to muscles. Medically it is used against muscle spasms, migraine and excessive sweating, and aesthetically against expression lines.

In depth: Botulinum Toxin →

Botulinum toxin antibodies

Neutralising antibodies the body can form against botulinum toxin, so that treatments lose their effect. The risk rises with high doses and short intervals; their frequency and relevance in aesthetic use are debated.

Botulism

A rare, life-threatening poisoning by the nerve toxin of Clostridium botulinum, usually from spoiled preserved foods. It causes paralysis that progresses from the eyes to the respiratory muscles.

Bouchard’s nodes

Osteoarthritis of the middle finger joints with knobbly swellings. It often occurs together with osteoarthritis of the end joints and frequently runs in families.

Bouveret syndrome

A rare form of gallstone ileus in which a large gallstone passes through a fistula into the duodenum and blocks the stomach outlet. Nausea and vomiting are typical, mainly in older people.

Bova score

A score for risk assessment in pulmonary embolism with stable circulation based on systolic blood pressure, heart rate, troponin and signs of right ventricular strain. It identifies patients at intermediate-high risk.

Bowditch effect

An increase in heart muscle force with rising heart rate, because more calcium accumulates in the muscle cells with more frequent beats. This effect is weakened in heart failure.

Bowenoid papulosis

Brownish or reddish papules in the genital area caused by high-risk HPV, histologically corresponding to a precancerous lesion. Regular check-ups are advisable because of a small risk of malignant change.

Bowman’s capsule

A double-walled capsule surrounding the capillary tuft of the glomerulus and collecting the filtered primary urine. From it, urine flows into the proximal tubule.

Bowman’s layer

A thin, cell-free layer of the cornea just beneath the epithelium. It does not regenerate after injury and is partly removed in surface laser procedures on the cornea.

Boxer’s fracture

A fracture of a metacarpal bone, usually of the little finger near the knuckle, often after a punch. Many can be treated without surgery, but malalignment must be checked.

BPRS

A short clinician-rated scale with 18 items such as anxiety, hallucinations and thought disorder, used mainly to measure the course of psychoses.

BPS (Behavioural Pain Scale)

A pain assessment scale for ventilated intensive care patients who cannot communicate, based on facial expression, arm movement and tolerance of the ventilator.

Braak stages

A neuropathological staging of the stepwise spread of tau deposits in Alzheimer’s disease (stages I to VI); a corresponding scheme exists for alpha-synuclein in Parkinson’s disease.

Brachial artery

The upper arm artery, running along the inner side of the arm and dividing at the elbow into the radial and ulnar arteries. Blood pressure is usually measured over it.

Brachialgia

Pain radiating into the arm, often originating in the cervical spine from irritated nerve roots.

Brachioradial pruritus

Itching and burning on the outer side of the forearms that often worsens after sun exposure. Irritation of cervical nerve roots and UV damage to skin nerves are discussed as causes.

Bracht manoeuvre

A manoeuvre in spontaneous breech birth in which the baby’s trunk, with the legs folded up, is guided upwards around the mother’s pubic symphysis without pulling.

Brachycephaly

A short, broad head caused by premature closure of both coronal sutures or positionally by frequent lying on the back of the head. Positional forms usually improve with repositioning.

Brachydactyly

Congenital shortening of fingers or toes due to short bones. It is usually harmless and hereditary but can be part of a syndrome.

Brachytherapy

Radiotherapy from inside, in which the radiation source is placed directly in or next to the tumour.

Braden scale

A nursing assessment tool for pressure ulcer risk based on sensory perception, moisture, activity, mobility, nutrition and friction. The lower the score, the higher the risk.

Bradford Hill criteria

A list of considerations such as strength, consistency, temporal sequence and dose-response relationship used to judge whether an observed association is likely to be causal. They are aids, not rigid rules.

Bradycardia

A heart rate that is too slow, with fewer than 60 beats per minute at rest. In trained athletes this is often normal.

Bradykinesia

Slowness of movement with difficulty starting and decreasing amplitude. It is a core symptom of Parkinson’s disease.

Bradykinin

A tissue hormone that widens blood vessels, increases their permeability and causes pain. Impaired breakdown is responsible for angioedema on ACE inhibitors and hereditary angioedema.

Bradypnoea

Slowed breathing with markedly fewer breaths per minute than normal, for example in opioid poisoning or raised intracranial pressure.

BRAF mutation

A change in the BRAF gene, most commonly the V600E variant, that permanently switches on a growth signalling pathway. It occurs in about half of melanomas and in some bowel, thyroid and lung tumours.

Bragard sign

An addition to the straight leg raise test: the straightened leg is raised to just below the pain threshold and the foot is then flexed upwards. If this increases pain radiating into the leg, it suggests nerve root irritation.

Branchio-oto-renal syndrome

An autosomal dominant inherited disease with malformations of branchial arch origin such as neck fistulas, ear malformations with hearing loss and kidney anomalies. The most common cause is changes in the EYA1 gene.

BRCA

Genes (BRCA1 and BRCA2) involved in DNA repair; mutations markedly increase the risk of breast and ovarian cancer.

See also: Breast cancer

Bread unit (carbohydrate exchange)

An older estimation unit for carbohydrates in diabetic nutrition, corresponding to 12 g of carbohydrate. It has largely been replaced by the carbohydrate unit of 10 g.

Breast cancer

A malignant tumour of the mammary gland and the most common cancer in women; men are rarely affected. Detected early, it is usually very treatable.

Breast-conserving therapy

Breast cancer treatment in which only the tumour is removed with a safety margin, followed by radiotherapy of the breast. For suitable tumour sizes it is usually as safe as mastectomy.

See also: Breast cancer

Breast implant exchange

Surgical replacement of breast implants, for example because of capsular contracture, implant defect, displacement or a wish for a different size. Breast implants are not lifelong products; follow-up procedures are therefore common.

Breast implant illness

A term for non-specific complaints such as fatigue, joint pain or poor concentration that affected people attribute to breast implants. A causal link has not been scientifically proven.

Breast reconstruction

Rebuilding the breast after mastectomy or for malformation, using implants or the patient’s own tissue. It can be done at the same time as cancer surgery or later and often requires several procedures.

Breast reduction

An operation to make the breasts smaller, often also for medical reasons such as back and neck pain.

In depth: Breast Reduction →

Breast self-examination

Regularly feeling and looking at one’s own breasts to notice changes such as lumps or skin dimpling. It does not replace medical screening but can help people know their own body better.

See also: Breast cancer

Breast tenderness

A feeling of tension or pain in the breast, often cyclical before a period or in pregnancy. New, one-sided or persistent symptoms should be medically assessed.

Breath-holding spell

A brief pause in breathing in toddlers after a fright, pain or anger, sometimes with turning blue or pale and brief loss of consciousness. It is harmless and usually disappears by school age.

Breathing exercises

Targeted exercises such as pursed-lip breathing, contact breathing or incentive spirometers intended to improve lung ventilation and loosen secretions. They are used in nursing to prevent pneumonia and in chronic lung disease.

Breathing therapy

Physiotherapy with breathing exercises and techniques to improve lung function, loosen mucus or relieve breathlessness, for example in COPD or after surgery.

Breech presentation

Position of the baby with the bottom or feet first; the baby can sometimes be turned from outside.

Bremelanotide

A melanocortin receptor agonist approved in the USA for reduced sexual desire in premenopausal women, injected under the skin as needed. The effect is moderate; nausea is common.

Brenner tumour

A rare, usually benign ovarian tumour made of transitional-type epithelial cells, often discovered by chance. Malignant forms are very rare.

Brensocatib

An inhibitor of the enzyme DPP1 that reduces the activation of pro-inflammatory enzymes in neutrophils. It is the first drug developed specifically to reduce exacerbations in bronchiectasis.

Brentuximab vedotin

An antibody-drug conjugate against CD30 that delivers a cell toxin directly into tumour cells. It is used mainly in Hodgkin lymphoma and certain T-cell lymphomas; nerve damage is common.

Breslow thickness

The thickness of a melanoma in millimetres from the uppermost living skin layer to the deepest tumour cell. It is one of the most important prognostic factors and determines the T stage.

Brexanolone

A derivative of the neurosteroid allopregnanolone given as a multi-day infusion for postnatal depression. It is approved in the USA; because of possible heavy sedation, monitoring is required.

Brexpiprazole

An atypical antipsychotic that acts as a partial agonist at dopamine D2 and serotonin receptors and is used in schizophrenia. A possible side effect is inner restlessness (akathisia).

Brexucabtagene autoleucel

An autologous CAR T-cell therapy against the surface marker CD19, used in adults with relapsed or refractory mantle cell lymphoma and B-cell acute lymphoblastic leukaemia.

Bridging veins

Veins that run from the brain surface through the space beneath the dura to the venous sinuses. Their tearing, for example in falls in older people or in shaking injuries, causes a subdural haematoma.

Brigatinib

A tyrosine kinase inhibitor against the altered enzyme ALK used in ALK-positive non-small cell lung cancer. It also works against brain metastases; respiratory symptoms can occur at the start.

Brimonidine

A drug that narrows blood vessels. As a gel it temporarily relieves facial redness in rosacea; as eye drops it lowers intraocular pressure.

Brincidofovir

An orally available lipid conjugate of the antiviral cidofovir that inhibits viral DNA synthesis inside cells. It is approved in the USA for treating smallpox; common side effects affect the gut and liver.

Brinzolamide

A carbonic anhydrase inhibitor in eye drops that reduces aqueous humour production and so lowers intraocular pressure. It is often combined with other glaucoma medicines.

Bristol stool scale

A picture scale with seven stool types from hard lumps to liquid. It helps describe constipation, diarrhoea and the course of bowel diseases consistently.

Brittle nails

Nails that split easily, separate into layers or tear, usually due to frequent contact with water and cleaning agents. Less often, iron deficiency, thyroid disorders or skin diseases are behind it.

Brivaracetam

An antiepileptic drug that, like levetiracetam, binds to the synaptic vesicle protein SV2A, but with higher affinity. It is used as add-on therapy for focal seizures.

Broad-spectrum antibiotic

An antibiotic that works against many different types of bacteria. It is useful while the organism is unknown but promotes resistance and side effects such as Clostridioides difficile infection.

Broad-spectrum sun protection

Sun protection that adequately reduces both UVB and UVA radiation. In the EU, UVA protection must reach at least one third of the stated sun protection factor.

Broca’s area

A brain region in the frontal lobe, usually on the left, that is important for producing speech. Damage leads to halting, effortful speech with relatively preserved understanding.

Brodalumab

A monoclonal antibody that blocks the interleukin-17 receptor A and is injected for moderate to severe plaque psoriasis. A signal for suicidal thoughts was seen in studies, so mental health is monitored.

Brodmann areas

A division of the cerebral cortex into about 50 fields according to their microscopic cell structure, published by Korbinian Brodmann in 1909. Many fields correspond to specific functions, for example area 17 to the visual cortex.

Brodsky scale

A grading of palatine tonsil size from 0 to 4 according to how much of the throat the tonsils occupy. It is used in tonsil enlargement and childhood sleep apnoea.

Brolucizumab

An antibody fragment against VEGF injected into the eye to treat wet macular degeneration and diabetic macular oedema. Rare but serious side effects include inflammation and vascular occlusion in the eye.

Bromage scale

A four-level scale for assessing motor block of the legs after spinal or epidural anaesthesia, from free movement to complete paralysis.

Bromazepam

An intermediate-acting benzodiazepine for anxiety and tension. Because of the risk of dependence it should only be used short term.

Bromhexine

A mucolytic that is converted to ambroxol in the body. It is intended to thin sticky bronchial mucus; its effectiveness is considered modest, and very rarely severe skin reactions occur.

Bromhidrosis

Unpleasant body odour from bacterial breakdown of sweat, mostly in the armpits and on the feet. Thorough hygiene, antiperspirants and treatment of heavy sweating help.

Bromocriptine

An older ergot-derived dopamine agonist that lowers prolactin and was formerly widely used in Parkinson’s disease. Because of nausea and circulatory side effects it has mostly been replaced by better-tolerated drugs.

Bronchi

The branching airways that lead from the windpipe into the two lungs and divide down to the air sacs.

Bronchial arteries

Small arteries, usually arising directly from the aorta, that supply the bronchi and lung tissue with oxygen-rich blood. They are the most common source of heavy coughing up of blood and are then selectively embolised.

Bronchial asthma

Chronic inflammation of the airways that causes episodes of bronchial narrowing. Typical symptoms are breathlessness, wheezing and cough, often triggered by allergens, infections or exercise.

In depth: Bronchial Asthma →

Bronchial breathing

A loud, high-pitched breath sound with a pronounced expiration that is normally heard only over the windpipe. Over the lung it indicates consolidated tissue, as in pneumonia.

Bronchial thermoplasty

A bronchoscopic procedure for severe asthma in which the smooth muscle of the bronchi is reduced with heat. It is rarely used today because effective biologics are available.

Bronchial toilet

Targeted removal of secretions from the airways by suctioning, chest physiotherapy or bronchoscopy, especially in ventilated or weakened patients. It helps prevent atelectasis and pneumonia.

Bronchiectasis

Permanently widened bronchi in which mucus collects, leading to chronic cough and frequent infections.

Bronchioles

The finest, cartilage-free branches of the bronchi, less than about one millimetre in diameter. They conduct air to the air sacs; their muscle can constrict in asthma.

See also: Bronchi, Alveoli, Bronchiolitis

Bronchiolitis

Inflammation of the smallest airways in infants, usually caused by RSV.

Bronchiolitis obliterans

Inflammatory scarring and closure of the smallest airways, for example after lung transplantation, infections or inhalation of toxic substances. The main symptoms are cough and increasing breathlessness.

Bronchitis

Inflammation of the bronchi, usually caused by viruses. The main symptom is cough, often with sputum. Chronic bronchitis is often caused by smoking.

Bronchodilator

A medicine that relaxes the bronchial muscles and so widens narrowed airways, such as beta-2 agonists or anticholinergics. Bronchodilators are mostly inhaled and are a cornerstone of asthma and COPD treatment.

Bronchodilator reversibility test

A lung function test before and after inhaling a bronchodilator. A clear improvement in forced expiratory volume in one second suggests reversible airway obstruction, as in asthma.

Bronchogenic cyst

A congenital fluid-filled cyst of malformed bronchial tissue, usually in the mediastinum. It often goes unnoticed but can cause symptoms through pressure, infection or bleeding.

Bronchophony

An auscultation finding in which whispered words are unusually clearly audible over consolidated lung tissue. It suggests, for example, pneumonia and complements percussion and vocal fremitus.

Bronchopulmonary dysplasia

A chronic lung disease mainly of very premature babies who needed oxygen or ventilation for a long time. It can cause increased susceptibility to infection and reduced lung function for years.

Bronchoscopy

Examination of the airways with a thin endoscope, during which tissue samples can also be taken.

Bronchospasm

Sudden narrowing of the bronchi due to cramp of the bronchial muscles, for example in asthma, allergy or irritation from a breathing tube. Wheezing and breathlessness are typical.

Brooker classification

A radiographic grading of heterotopic ossification after hip replacement into four grades up to bony bridging of the joint. Higher grades can markedly restrict mobility.

Broselow tape

A colour-coded measuring tape used in emergencies to estimate a child’s weight, drug doses and equipment sizes from body length. It reduces dosing errors.

Broström procedure

Anatomical repair of the outer ankle ligaments in chronic instability, in which the stretched ligaments are tightened and reattached to the bone. In the modification according to Gould, the extensor retinaculum is also used for reinforcement.

Brotizolam

A short-acting benzodiazepine sleeping pill for temporary difficulty falling or staying asleep. Like all benzodiazepines, it can cause dependence and impair alertness the next day.

Brow lift

Raising low-set eyebrows by surgery, threads or botulinum toxin.

Brow ptosis

Drooping of the eyebrow, usually age-related or after facial nerve palsy, which places an extra load on the upper eyelid. It is treated surgically with a brow lift and must be recognised before eyelid surgery.

Brown adipose tissue

A special fat tissue that converts energy into heat; it can be activated by cold.

Brown-Séquard syndrome

One-sided damage to the spinal cord with a characteristic pattern: paralysis and loss of deep sensation on the injured side, loss of pain and temperature sensation on the opposite side.

Brown syndrome

An eye movement disorder in which the tendon of the superior oblique muscle cannot glide freely, so the eye cannot be raised when looking inward. It is usually congenital but can also be acquired.

Brucella

A genus of bacteria transmitted from livestock such as goats, sheep and cattle, often via raw milk products. They cause brucellosis with undulating fever.

Brucellosis

A bacterial zoonosis transmitted mainly through raw milk products or contact with infected livestock. Undulating fever with sweating and joint pain is typical.

Bruch’s membrane

A thin layer between the retinal pigment epithelium and the choroid through which nutrients and waste products are exchanged. Deposits in it, called drusen, are an early sign of age-related macular degeneration.

Brückner test

A transillumination test in which both pupils are illuminated simultaneously with an ophthalmoscope. Differences in the red reflex can reveal squint, refractive errors or opacities such as retinoblastoma.

Brudzinski sign

Reflex drawing up of the legs when the head is passively bent forward. It indicates meningeal irritation, for example in meningitis.

BRUE

A brief, sudden and resolved event in an infant with changes in breathing, colour or muscle tone. In low-risk cases, extensive investigations are usually not needed.

Brugada algorithm

A four-step ECG scheme for distinguishing ventricular tachycardia from supraventricular tachycardia with bundle branch block when the QRS complex is broad. Not to be confused with Brugada syndrome.

Brugada syndrome

An inherited disorder of the heart’s ion channels with typical ECG changes and an increased risk of dangerous ventricular arrhythmias, often at rest or with fever. High-risk patients receive an implantable defibrillator.

Brunner’s glands

Glands in the submucosa of the duodenum that secrete an alkaline, mucous fluid and protect the lining from stomach acid.

Bruxism

Grinding or clenching of the teeth, often at night and stress-related; it can damage the teeth and jaw joints.

In depth: Teeth Grinding (Bruxism) →

BTK inhibitors

A group of drugs that inhibit Bruton tyrosine kinase, a key enzyme of B-cell signalling. They are used mainly in chronic lymphocytic leukaemia and certain lymphomas; typical side effects include bleeding and atrial fibrillation.

Budd-Chiari syndrome

A rare blockage of the hepatic veins, usually by blood clots, with abdominal pain, ascites and liver enlargement.

Budesonide

A corticosteroid that acts mainly locally and is rapidly broken down in the liver after absorption. It is inhaled for asthma or used as a gut preparation for Crohn’s disease and microscopic colitis.

Budipine

A Parkinson’s medicine with NMDA-antagonistic and anticholinergic effects, used mainly against tremor. Because of possible QT prolongation, ECG monitoring is mandatory.

Buffalo hump

A fat pad at the back of the neck, typical of cortisol excess in Cushing’s syndrome or during long-term corticosteroid therapy.

Bulbocavernosus reflex

A superficial reflex in which pressure on the glans or clitoris causes the pelvic floor to contract. It tests the sacral segments S2 to S4; its return marks the end of spinal shock.

Bulevirtide

An antiviral drug that blocks entry of the hepatitis D virus into liver cells by occupying the bile acid transporter NTCP. It is injected under the skin daily and is approved for treating chronic hepatitis D.

Bulimia nervosa

An eating disorder with binge eating followed by compensatory measures; it is very treatable.

Bulk-fill composite

A resin filling material that can be placed and cured in layers of up to four or five millimetres in one step. This saves time compared with the classic layering technique.

Bulla

A fluid-filled skin blister larger than about half a centimetre, for example in burns or blistering autoimmune diseases.

Bumetanide

A potent loop diuretic that increases salt and water excretion by the kidneys. It is used for fluid retention; checks of potassium and sodium are important.

Bunny lines

Oblique wrinkles on the sides of the bridge of the nose that appear when wrinkling the nose or laughing. They are sometimes treated with botulinum toxin; altered facial expression or a drooping upper lip are possible.

Bupivacaine

A long-acting local anaesthetic used for spinal and epidural anaesthesia and nerve blocks. If accidentally injected into a vessel, it is more cardiotoxic than other local anaesthetics.

Buprenorphine

An opioid used as a patch for chronic pain and in substitution treatment for opioid dependence. It has a ceiling effect for respiratory depression.

Bupropion

An antidepressant that inhibits the reuptake of dopamine and noradrenaline and is also used to help stop smoking. It lowers the seizure threshold and is unsuitable in epilepsy.

Burch colposuspension

An operation for stress incontinence in which the vaginal tissue next to the urethra is lifted with sutures to ligaments of the pubic bone. It is less common today since tape procedures have become widespread.

Burkholderia

A genus of Gram-negative environmental bacteria. Burkholderia cepacia endangers mainly people with cystic fibrosis; B. pseudomallei causes tropical melioidosis.

Burkitt lymphoma

A very fast-growing B-cell lymphoma often associated with the Epstein-Barr virus in Africa. Despite its aggressiveness it is often curable with intensive chemotherapy.

Burnout

A state of deep emotional, physical and mental exhaustion due to prolonged overload, usually at work. It is not a separate disease but a risk factor, for example for depression.

Burosumab

An antibody against the hormone FGF23, which is overproduced in X-linked hypophosphataemia and wastes phosphate through the kidneys. Treatment improves phosphate levels and bone healing in rickets.

BURP manoeuvre

A manoeuvre in difficult intubation in which the larynx is pressed from outside backwards, upwards and to the right to improve the view of the vocal cords.

Bursitis

Inflammation of a bursa, for example at the elbow or knee, often due to overuse.

Burst fracture

A fracture of a vertebral body from axial compression in which fragments can also be pushed into the spinal canal. Surgery depends on stability and nerve involvement.

Buruli ulcer

A tropical skin infection caused by Mycobacterium ulcerans that begins with painless nodules and can lead to large, deep ulcers. Early antibiotic treatment prevents permanent damage.

Buserelin

A GnRH agonist that, after initial stimulation, suppresses hormone production by the gonads. It is used in prostate cancer, endometriosis and fertility treatment.

Buspirone

An anti-anxiety drug acting on 5-HT1A serotonin receptors. Unlike benzodiazepines it causes little drowsiness and no dependence but takes several weeks to work.

Busulfan

An alkylating cytostatic used today mainly in high doses for conditioning before stem cell transplantation. Anti-seizure medicines are given preventively; other risks include veno-occlusive disease of the liver.

Butylscopolamine

An antispasmodic that relaxes the smooth muscle of the stomach, bowel, bile ducts and urinary tract and is used for cramping abdominal pain. Because it hardly reaches the brain, central side effects are rare.

Bypass

A surgically created route around a narrowed or blocked blood vessel, for example coronary bypass surgery in coronary heart disease.

Byssinosis

A respiratory disease from years of inhaling cotton, flax or hemp dust. Typical is chest tightness that initially occurs mainly on the first working day after the weekend.

Bacillary angiomatosis

Infection with Bartonella species in people with severe immunodeficiency. Red, vascular skin nodules form that can resemble Kaposi’s sarcoma but respond well to antibiotics.

Balkan nephropathy

Chronic kidney disease that occurred frequently in villages along the Danube. The cause is thought to be intake of aristolochic acid via contaminated grain; those affected also have an increased risk of urinary tract cancer.

Balloon dilation of the Eustachian tube

Procedure in which a small balloon is inserted through the nose into the Eustachian tube and briefly inflated. It is used for chronic poor ventilation of the middle ear; long-term results are still being studied.

Bannwarth syndrome

Most common form of early neuroborreliosis, with inflammation of the meninges and nerve roots. Burning nerve pain that is worse at night and often facial palsy are typical; with antibiotic treatment the prognosis is usually good.

Bartonella henselae

Bacterium transmitted mainly by scratches or bites from young cats that causes cat scratch disease with swollen lymph nodes. In immunocompromised people it can lead to bacillary angiomatosis.

Bathmotropy

Influence on the excitability of the heart muscle, i.e. how easily a stimulus triggers a response. A positive bathmotropic effect can favour extra beats.

Batoclimab

Monoclonal antibody that blocks the neonatal Fc receptor (FcRn) and so speeds up the breakdown of IgG antibodies. It is being tested in studies in autoimmune diseases such as myasthenia gravis and thyroid eye disease.

Beer potomania

Hyponatraemia in people who drink large amounts of beer and eat hardly any solid food. In treatment, sodium must be raised particularly slowly, otherwise osmotic demyelination syndrome can occur.

Beige fat cells

Fat cells in white adipose tissue that can transform into heat-producing cells, for example in the cold. They then contain many mitochondria and thermogenin, similar to brown fat.

Belching

Escape of air from the stomach through the oesophagus and mouth. Occasional belching is normal; frequent belching can be related to air swallowing, reflux or stomach complaints.

Beremagene geperpavec

Topical gene therapy gel in which an attenuated herpes virus delivers intact copies of the COL7A1 gene into skin cells. It is applied to wounds in dystrophic epidermolysis bullosa to promote healing.

Berotralstat

Oral inhibitor of plasma kallikrein that reduces the formation of bradykinin. It is used for long-term prevention of swelling attacks in hereditary angioedema.

Bezuclastinib

Tyrosine kinase inhibitor that specifically targets the mutated KIT variant D816V. It is being studied in systemic mastocytosis and gastrointestinal stromal tumours.

Bilirubin metabolism

Breakdown pathway of haemoglobin: bilirubin is formed from haem, conjugated with glucuronic acid in the liver, excreted with bile and further broken down in the gut. Disorders lead to jaundice.

Birch bark extract

Gel made from a dry extract of birch bark containing triterpenes such as betulin. It is approved for treating superficial wounds in epidermolysis bullosa and is intended to support wound healing.

Blastomyces dermatitidis

Fungus found in moist soils of North America, especially along large rivers and lakes. It causes blastomycosis, which can affect the lungs, skin and bones.

Blumer’s shelf

Palpable hard bulge in the pouch of Douglas on rectal examination. It is caused by deposits of tumour cells in the abdominal cavity, for example in stomach or bowel cancer.

Bonding

Development of the emotional bond between parents and newborn, especially in the first hours after birth. Skin-to-skin contact supports this process and breastfeeding.

Borrelial lymphocytoma

Bluish-red, soft swelling of the skin, typically on the earlobe in children or on the nipple. It is an early skin manifestation of Lyme disease and regresses with antibiotic treatment.

Botfly

Flies whose larvae develop in the skin of animals. In humans, the human botfly in Latin America in particular causes furuncle-like myiasis with a small breathing opening for the larva.

Bowel cancer screening

Early detection of bowel cancer and its precursors by a stool test for hidden blood or colonoscopy. In Germany, people with statutory health insurance are entitled to it from the age of 50.

Bowel obstruction (ileus)

Standstill of the passage through the bowel, either mechanical or due to paralysis of the bowel; an emergency.

Bowel sounds

Sounds of bowel movement audible with a stethoscope. Their absence suggests paralysis of the bowel; high-pitched, tinkling sounds can indicate a mechanical bowel obstruction.

Brain fog

Colloquial term for a state of poor concentration, slowed thinking and forgetfulness. It occurs, for example, after infections such as long COVID, with lack of sleep or during the menopause.

Brodie abscess

Localised pus-filled cavity in bone as a form of subacute osteomyelitis. It usually occurs in adolescents in the region of the tibia and often causes only local pain that is worse at night.

Burning pain

Pain perceived as burning, typical of nerve damage as in polyneuropathy or after shingles. It often responds poorly to conventional painkillers.

Buschke-Ollendorff syndrome

Rare autosomal dominant disease caused by mutations in the LEMD3 gene. It combines skin-coloured to yellowish connective tissue naevi with small, harmless areas of bone thickening (osteopoikilosis), which should not be mistaken for metastases on X-ray.

Back to the Medical Encyclopedia overview

Medical Encyclopedia: B

B cells

B-Lynch suture

B symptoms

Baastrup syndrome

Babesiosis

Babinski reflex

Babkin reflex

Baby blues

Bacillus anthracis

Bacillus cereus

Bacitracin

Baclofen

Bacteraemia

Bacteria

Bacterial spores

Bacterial vaginosis

Bactericidal

Bacteriostatic

Bacteriuria

Bacteroides fragilis

Baden-Walker classification

Bado classification

Bag-valve-mask ventilation

Bagolini test

Bainbridge reflex

Baker classification

Baker’s cyst

Bakri balloon

Bakuchiol

Balanced anaesthesia

Balanitis

Balantidiasis

Bálint syndrome

Ballard score

Baller-Gerold syndrome

Ballismus

Balloon enteroscopy

Balloon sinuplasty

Balneophototherapy

Balneotherapy

Baloxavir

Balsalazide

Balthazar score

Bamboo spine

Bambuterol

Band keratopathy

Banff classification

Bankart lesion

Bankart repair

Bannayan-Riley-Ruvalcaba syndrome

BAP1 tumour predisposition syndrome

Bárány pointing test

Bardet-Biedl syndrome

Bariatric surgery

Baricitinib

Barlow test

Baroreceptor

Baroreflex

Barotrauma

Barré arm drift test

Barrett’s oesophagus

Barrier nursing

Barth syndrome

Barthel index

Bartholin’s cyst

Bartholin’s gland

Bartholinitis

Barton fracture

Bartonellosis

Bartsocas-Papas syndrome

Bartter syndrome

Basal body temperature

Basal-bolus therapy

Basal cell carcinoma

Basal cell layer

Basal ganglia

Basal insulin

Basal stimulation

BASDAI