Uniform central cyanosis is cyanosis of both upper and lower limbs along with cyanosis of lips and tongue. In differential cyanosis, there is cyanosis of lower limbs without cyanosis of upper limbs. This occurs typically in patent ductus arteriosus with reversal of shunt due to severe pulmonary hypertension. In a neonate differential cyanosis can occur due to persistent pulmonary hypertension, aortic arch hypoplasia, interrupted aortic arch, critical coarctation, and critical aortic stenosis with patent ductus arteriosus.
Reverse differential cyanosis with cyanosis of upper limbs and no cyanosis of lower limbs occurs in more complex congenital heart diseases. Reverse differential cyanosis can occur in complete transposition of great arteries or Taussig-Bing anomaly with reversal of ductal flow due to severe pulmonary hypertension.
