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Compartment syndrome
Compartment syndrome: raised pressure within a fascial muscle compartment causing ischemia; acute form is a trauma emergency treated by fasciotomy, chronic exertional form causes exercise-induced leg pain; delta pressure <30 mm Hg guides diagnosis.
Compartmental models (epidemiology)
Compartmental models in epidemiology divide a population into compartments such as SIR or SEIR states and use equations for movement between them. Founded on Kermack and McKendrick's 1927 work, they contrast with agent-based models and are widely used for outbreak forecasting and intervention analysis.
Compassion-focused therapy
Compassion-focused therapy (CFT) is a third-wave psychotherapy developed by Paul Gilbert around 2000 that trains clients in compassion skills to reduce shame and self-criticism, with trials showing reduced depression.
Compassionate use
Compassionate use, formally called expanded access in the United States, is a regulatory pathway that lets patients with serious or life-threatening conditions receive investigational drugs outside clinical trials.
Compatibility testing (transfusion medicine)
Compatibility testing, also called pretransfusion testing, is the set of laboratory procedures, including ABO and RhD typing, antibody screening, and crossmatch, that confirm a blood component is safe for a specific patient.
Compensatory emphysema
Compensatory emphysema (ICD-11 CB40.4, ICD-10 J98.3) is overinflation of normal lung tissue when another portion is destroyed or removed, as after pneumonectomy, pneumonia, pleural effusion, or pneumothorax; unlike true emphysema it involves no alveolar destruction.
COMPERA study
The COMPERA study is a European registry founded in Germany in 2007 documenting drug therapy and outcomes for pulmonary hypertension, with more than 13,000 patients enrolled across Europe.
Complement component 3 deficiency
Complement component 3 deficiency (C3 deficiency, ORPHA:280133) is a rare autosomal recessive primary immunodeficiency causing severe recurrent encapsulated bacterial infections, glomerulonephritis, and SLE-like disease in childhood.
Complement Hemolytic Activity Assay
Complement Hemolytic Activity Assay (CH50, total hemolytic complement): functional blood test measuring total classical and terminal complement pathway activity by lysis of antibody-sensitized sheep red blood cells; used to screen complement deficiency and monitor lupus.
Complement system
Complement system: 40+ plasma proteins of innate immunity; classical, lectin, and alternative pathways converge on C3 cleavage, driving opsonization, inflammation, and MAC lysis; dysregulation causes aHUS, AMD, PNH, hereditary angioedema.
Complement-dependent cytotoxicity
Complement-dependent cytotoxicity is a crossmatch assay, developed by Paul Terasaki, that detects recipient antibodies killing donor cells before transplantation; a 1969 study showed positive-crossmatch kidney transplants failed immediately.
Complementary colors
Complementary colors are color pairs that mix to neutral (white light, grey pigment) and sit opposite on the color wheel, such as red/green, yellow/violet, and blue/orange; they drive simultaneous contrast, afterimages, and painterly contrast techniques.
Complete atrioventricular block
Complete atrioventricular block (third-degree AV block, complete heart block, ICD-11 BC63.2, ICD-10 I44.2): total absence of AV conduction with independent atrial and ventricular rhythms, escape rhythms at 20-50 bpm, treated with permanent pacing.
Complete atrioventricular septal defect
Complete atrioventricular septal defect (complete AV canal, CAVC, complete AVSD): congenital heart defect with common AV valve, primum ASD, and inlet VSD; repaired at 3-6 months.
Complete blood count
Complete blood count (CBC, full blood count): a common blood test measuring red cells, white cells, platelets, hemoglobin, hematocrit, and MCV; automated since Coulter's 1954 counter, used for diagnosis and monitoring, not recommended for screening well adults.
Complete Denture
Complete denture: removable prosthesis replacing all teeth in an edentulous maxillary or mandibular arch (full denture). Success rests on retention, stability, and support; lower dentures are harder; two-implant overdentures improve outcomes.
Complete lymph node dissection
Complete lymph node dissection (CLND) is a surgical oncology procedure removing most or all lymph nodes in a regional basin, most often the axilla, groin, neck, or retroperitoneum.
Complete septate uterus
Complete septate uterus (total septate uterus, ORPHA:180126, ICD-10 Q51.2) is a congenital malformation where a septum runs from the uterine fundus to the cervical os, raising miscarriage risk; treated by hysteroscopic resection.
Complete uterovaginal prolapse
Complete uterovaginal prolapse (procidentia, ICD-11 GC40.34) is stage 3-4 descent of uterus, cervix, and upper vagina below the hymen or with complete eversion, caused mainly by childbirth-related pelvic floor damage and treated with pessaries or prolapse surgery.
Completion thyroidectomy
Completion thyroidectomy is a second operation removing the remaining thyroid tissue after a partial thyroidectomy, typically when final pathology shows cancer that justifies removing the whole gland.
Complex (psychology)
Complex (psychology): Jung's feeling-toned complex, an emotionally charged group of ideas acting semi-independently, discovered via the Burghölzli word association experiments; basis of his complex psychology, distinct from Freud's Oedipus and Adler's inferiority complexes.
Complex decongestive therapy
Complex decongestive therapy (CDT) is a multimodal conservative treatment for lymphedema combining manual lymph drainage, compression bandaging, skin care, exercise, and education, with an intensive phase followed by lifelong maintenance.
Complex febrile seizures
A complex febrile seizure is a fever-related seizure in a young child that is focal, lasts 15 minutes or more, recurs within 24 hours, or causes lasting weakness.
Complex post-traumatic stress disorder
Complex post-traumatic stress disorder (CPTSD, C-PTSD), ICD-11 6B41: prolonged repeated trauma syndrome combining PTSD core symptoms with disturbances in affect regulation, self-concept, and relationships; 1–8% population prevalence; not in DSM-5.
Complex regional pain syndrome
Complex regional pain syndrome (CRPS), formerly reflex sympathetic dystrophy or causalgia, is a chronic limb pain condition after trauma or surgery; diagnosed clinically via Budapest criteria, with no high-certainty evidence for any therapy.
Complex renal cyst
Complex renal cyst, also called Bosniak IIF or higher cystic renal mass, a kidney cyst with septa, thickened wall, or enhancement. Malignancy risk rises from about 7% (IIF) to 55% (III) and 91% (IV); IIF needs imaging follow-up.
Compliance (physiology)
Compliance (physiology): the ease of volume expansion per pressure change (C=ΔV/ΔP) in heart chambers and vessels; ventricular diastolic compliance, venous capacitance 30 times arterial, and clinical diastolic dysfunction.
Complicated crown fracture
Complicated crown fracture: a traumatic tooth fracture through enamel and dentin exposing the dental pulp, usually a maxillary incisor in children 6-12. Treated by vital pulp therapy, mainly partial pulpotomy, with 75-97% success.
Complicated crown-root fracture
Complicated crown-root fracture (ICD-11 NA0D.05): traumatic tooth fracture involving enamel, dentin, cementum, and exposed pulp, extending below the gingiva; about 5% of permanent-dentition dental trauma, treated by pulpotomy or root canal treatment plus extrusion or reattachment.
Complication (medicine)
Complication (medicine): an unfavorable medical problem arising during a disease or after a procedure or treatment. Also called oslozhenie in Russian usage; distinguished from comorbidity and adverse events; graded surgically by the Clavien-Dindo classification.