Cyanosis is characterized by bluish discoloration of skin and mucous membranes. Cyanosis is usually a sign of an underlying condition rather than being a disease in itself. The most common symptoms of the condition are bluish discoloration of the lips, fingers, and toes.
Cyanosis can be evident at birth due to the presence of a heart malformation that permits blood that is not fully oxygenated to enter the arterial circulation. Cyanosis can also appear at any time later in life and often accompanies conditions in which lung function is compromised (resulting in an inability to fully oxygenate the blood) or conditions in which the heart's pumping function is compromised. The presence of abnormal forms of hemoglobin or other abnormalities of the blood cells can also sometimes cause cyanosis. The medical term for lowered oxygen level is hypoxia, the term anoxia refers to the absence of oxygen. Pseudo cyanosis is the appearance of cyanosis that is not associated with reduced oxygen delivery to the tissues. Most causes are related to the ingestion of metals (such as silver or lead) or drugs/toxins.