Preduodenal portal vein: a cause of prenatally diagnosed duodenal obstruction.

Preduodenal portal vein is a rare congenital anomaly that causes high intestinal obstruction. The authors report on a newborn who was diagnosed as having duodenal obstruction at 30 weeks' gestation. During surgery the patient was found to have duodenal obstruction caused by a preduodenal portal vein. Malrotation was an associated finding. Treatment consisted of Ladd's procedure and a diamond-shaped duodenoduodenostomy performed anterior to the portal vein.