Life and health

Contraindication

A contraindication is a condition, such as pregnancy or an allergy, that is a reason not to use a drug, procedure, or surgery because it may be harmful.

Contralateral prophylactic mastectomy

Contralateral prophylactic mastectomy (CPM) is the surgical removal of the cancer-free breast in a patient with unilateral breast cancer, cutting contralateral cancer risk by 90 to 96%.

Contrast (vision)

Contrast in vision is the difference in lightness or darkness between an object and its background; contrast sensitivity testing can detect eye diseases that standard acuity measurement misses.

Contrast echocardiography is cardiac ultrasound performed after intravenous injection of gas microbubbles that opacify the blood pool, used when up to 20% of echocardiograms have poor endocardial border definition.

Contrast Sensitivity

Contrast sensitivity is the ability of the visual system to detect small differences in brightness between an object and its background, measured clinically with tests like the Pelli-Robson chart.

Contrast-enhanced computed tomography

Contrast-enhanced computed tomography (CECT) is a CT technique in which intravenous iodinated contrast makes vessels, organs, and lesions visible, used for tumors, infection, and vascular disease.

Contrast-enhanced mammography

Contrast-enhanced mammography (CEM) is a dual-energy breast imaging technique that uses injected iodinated contrast to reveal tumor blood vessels, with sensitivity approaching MRI at lower cost.

Contrast-enhanced ultrasound

Contrast-enhanced ultrasound (CEUS) is an imaging technique that injects gas microbubble contrast agents to image blood flow and tissue perfusion in real time during ultrasound.

Control coefficient (biochemistry)

Control coefficient (biochemistry): normalized sensitivity in metabolic control analysis, from Kacser & Burns 1973 and Heinrich & Rapoport 1974, measuring fractional change of flux or metabolite concentration per fractional change in one enzyme's rate; flux coefficients sum to one, concentration coefficients to zero.

Control of fire by early humans

Control of fire by early humans: hominins' unique ability to use, maintain, and make fire, from burnt material at 1.5 Ma sites, Wonderwerk Cave and Gesher Benot Ya'aqov, to the earliest fire-making evidence at Barnham, England, 400,000 years ago.

Controlled before-after study

A controlled before-after study is a quasi-experimental design measuring outcomes before and after an intervention in both intervention and comparison groups, without randomization, to estimate the intervention's effect.

Controlled burn

Controlled burn, also called prescribed fire or prescribed burn: planned ignition by fire specialists under set weather conditions to cut fuels and wildfire severity; reduces severity 62–72% but weakens under extreme fire weather.

Controlled Environment

Controlled environment (Environment, Controlled): an enclosed space with technologically regulated air cleanliness, temperature, humidity, and pressure, spanning cleanrooms (ISO 14644, formerly FED-STD-209), hospital isolation and protective rooms, and spacecraft ECLSS cabins.

Controlled interrupted time series analysis

Controlled interrupted time series (CITS) analysis is a quasi-experimental design that evaluates health or policy interventions by comparing before-and-after trends between an exposed population and an unexposed control.

Controlled ovarian stimulation

Controlled ovarian stimulation (COS) is a fertility treatment in which hormonal drugs make the ovaries mature multiple eggs in a single cycle, most often as the first step of in vitro fertilization.

Controlled substances in veterinary practice

Controlled substances in veterinary practice are narcotics, anesthetics, and sedatives whose storage, ordering, recordkeeping, and destruction are regulated by government agencies, including the DEA in the United States.

Controlled traffic farming

Controlled traffic farming (CTF) is a crop production system that restricts all machinery to permanent wheel tracks, keeping about 70–80% of farmland free of soil compaction.

Controlled ventilation

Controlled ventilation is a mode of mechanical ventilation in which the ventilator delivers every timed breath regardless of patient effort, used in apneic or paralyzed patients.

Controlling nutritional status score

The Controlling Nutritional Status (CONUT) score is a laboratory screening tool that quantifies malnutrition from three routine blood tests: serum albumin, total cholesterol, and total lymphocyte count.

Controversies in autism

Controversies in autism: disputes over rising prevalence (1 in 31 U.S. children, 2025 CDC), the refuted vaccine-autism myth from Wakefield's 1998 Lancet paper, neurodiversity versus the medical model, and ABA therapy ethics.

Contusion of abdominal wall

Contusion of abdominal wall (ICD-10 S30.11, ICD-11 NB50.3): blunt soft-tissue bruise of the abdominal wall muscles without significant internal injury, caused by direct force such as a fist, foot, or seatbelt; treated with ice, rest, and analgesics.

Contusion of ankle

Contusion of ankle (ICD-11 ND11.1) is a superficial bruising injury of ankle soft tissue from a direct blow, causing pain, swelling, and bruising, managed with PRICE care and Ottawa Ankle Rules screening for fracture.

Contusion of bladder

Contusion of bladder (ICD-11 NB92.20) is a bruise of the bladder wall, AAST grade 1, the most common and least severe bladder injury; it is a diagnosis of exclusion in hematuria after blunt trauma and needs only observation.

Oct 20, 2026

Contusion of breast

Contusion of breast (ICD-10 S20.0; ICD-11 NA80.1) is a breast bruise from blunt trauma crushing superficial vessels without breaking skin, causing pain, swelling, and ecchymosis that usually resolve within 21 days; complications include hematoma and fat necrosis.