Peripheral cyanosis is the result of decreased blood flow to the skin secondary to vasoconstriction. Common causes of peripheral cyanosis include shock and exposure to cold. Peripheral cyanosis is transient and not associated with clubbing of the fingernails. Fingers and toes are often clubbed. Clubbing may also be familial and may not be associated with decreased arterial oxygen saturation.
Patients often know when clubbing runs in the family.