Life and health

Complement receptor 1

Complement receptor 1 (CR1, CD35), a 30-CCP-domain transmembrane RCA-family protein on leukocytes, erythrocytes, and podocytes, binds C3b/C4b, accelerates convertase decay, acts as a factor I cofactor, and clears immune complexes.

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.

Complementary DNA

Complementary DNA (cDNA, copy DNA): synthetic DNA reverse transcribed from mRNA by reverse transcriptase, discovered by Baltimore and Temin in 1970; intron-free, used in cloning, cDNA libraries, and RNA-seq.

Complementation (genetics)

A complementation test combines two recessive mutations in one organism to determine whether they affect the same gene; a mutant trans-heterozygote means the mutations are allelic.

Complementation assay

A complementation assay is a genetic test that determines whether two mutations causing the same recessive phenotype are in the same gene, by combining them in one organism.

Complementation test

The complementation test, also called the cis–trans test, is a genetic cross that determines whether two similar recessive mutations are alleles of one gene or of two different genes.

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 I deficiency

Complex I deficiency is a mitochondrial disease in which the first enzyme of the respiratory chain shows markedly reduced activity, accounting for about a third of childhood mitochondrial disease cases.

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.

Complication after organ transplantation

A complication after organ transplantation is any adverse medical condition developing in a recipient as a result of the transplant, rejection, infection, metabolic effects of immunosuppressive drugs, or malignancy.

Complications after hematopoietic stem cell transplantation

Complications after hematopoietic stem cell transplantation (HSCT, HCT) range from early infections, acute GVHD, and sinusoidal obstruction syndrome to late chronic GVHD, cardiovascular, endocrine, renal, neurologic, and second-cancer sequelae, with >70% of 10-year survivors developing chronic health conditions.