IN THE early human embryo the alimentary canal communicates freely with the yolk sac. This channel is known as the omphalomesenteric duct and is also referred to as the vitellointestinal duct. The embryology is well described by Cullen.1 As development proceeds, the duct becomes narrower and lies within the umbilical cord. Under normal conditions the duct disappears and the intestine has no connection with the yolk sac. Under abnormal conditions all, or any part, of the duct may persist, resulting in various anomalies as described by Benson2 (Fig 1). In this paper we are concerned only with the situation in which there is complete patentcy of the duct (Fig 1F). This anomaly is often referred to as an "umbilical enteric fistula" as well as the more classic terms, patent omphalomesenteric duct or patent vitellointestinal duct.
Diagnosis should not be difficult if the possibility of this anomaly is