Antenatal sonographic diagnosis of single umbilical artery.

Seven fetuses with a single umbilical artery were detected at the perinatal ultrasound unit of Yale University during a one-year period. Other sonographic abnormalities included hydramnios (four cases) and intrauterine growth retardation (two cases). Two neonates died shortly after birth, two others survived with abnormalities, and three were normal. The varied sonographic appearances of single umbilical artery are illustrated and contrasted with sonograms of normal umbilical cords.