Megacystis associated with an umbilical cord cyst: a sonographic feature of a patent urachus in the first trimester.

Objective: The purpose of this series was to report the first-trimester sonographic findings, antenatal course, and outcome in fetuses with a patent urachus.

Methods: We conducted a review of ultrasound reports and medical charts from 3 pregnancies complicated by a congenital patent urachus detected in the first trimester.

Results: All 3 fetuses had megacystis and an umbilical cord cyst close to the fetal abdominal insertion that was detected in the first trimester.