Cyanosis

Cyanosis is a term for bluish discolouration of the skin and mucous membranes with a higher content of deoxygenated hemoglobin in the blood. This coloration is manifested when the content of non-oxygenated hemoglobin in the blood is above  50 g/l. Therefore, cyanosis is observed more often in polyglobulia than in anemia (when the total hemoglobin content in the blood is reduced).