Which term means blue skin due to lack of oxygen?

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

Answer: (B)

Cyanosis is the term for blue discoloration of the skin due to lack of oxygen. When oxygen in the blood drops, hemoglobin becomes more deoxygenated and takes on a darker blue color, which shows through the skin—especially in thin areas like the lips and nail beds. This can occur centrally, from low arterial oxygen, or peripherally, from reduced blood flow. The other terms refer to unrelated things or are not the standard medical term for this finding: the skull is the cranium, a bladder infection is cystitis, and cyanoderma is not the common term used for oxygen-related bluish skin.