Which term describes blue skin due to lack of oxygen?

• A. Cyanosis
• B. Cystitis
• C. Cyanoderma
• D. Cribriform

Answer: (A)

Blue skin from not enough oxygen is called cyanosis. This happens when hemoglobin is highly deoxygenated, giving blood a darker blue hue, which becomes visible in the skin and mucous membranes, especially in the lips, tongue, and nail beds. There are two main forms: central cyanosis, reflecting poor oxygenation in the lungs or heart, and peripheral cyanosis, due to reduced blood flow or cold exposure. The term comes from cyan- (blue) and -osis (a condition). The other terms refer to different things—cystitis is a bladder infection, cribriform means sieve-like, and cyanoderma is not the standard term used for this skin change.