Preduodenal portal vein: Two cases with differing presentation.

Preduodenal or precholedochal veins are rare developmental anomalies of considerable surgical importance. Injury to these structures because of failure to recognize them during operations for unrelated diseases may result in thrombosis or hemorrhage. We recently encountered this anomaly twice, once in a newborn infant with duodenal obstruction and once in a 54-year-old woman undergoing cholecystectomy. The preduodenal vein was not the primary cause of obstruction in the infant, but injury to the previously unrecognized percholedochal vein in the woman resulted in a considerable loss of blood. Besides describing and illustrating these two cases, we also discuss the anatomy and the embryology of these structures and briefly review the patterns of 44 previously reported cases that we found.