Prenatal Diagnosis and Clinical Course of a Patent Urachus Associated with an Allantoic Cord Cyst and a Giant Umbilical Cord.

Umbilical cord cysts are rare and the various differential diagnoses influence both management of delivery and postnatal care. Differential diagnoses of umbilical cord cysts include pseudo-cysts, omphalocele, bladder exstrophy, omphalomesenteric duct cysts and other urachal anomalies. Communication between the cyst and the fetal bladder is a hallmark of patent ductus urachus, which has an estimated incidence of 1-2:100,000 and may be detected prenatally by high-resolution ultrasound (Persutte WH et al. J Ultrasound Med 1988; 7: 399-403; Wildhaber BE et al. Arch Dis Child Fetal Neonatal Ed 2005; 90: F535-536). We present a case of a patent ductus urachus initially presenting as an allantoic cord cyst followed by edematous swelling of the umbilical cord.