Allantoic cyst - an unusual umbilical cord swelling.

We report a baby with an unusual umbilical cord swelling. On the antenatal scans, a cystic area within the umbilical cord near its insertion onto the abdominal wall was detected. Postnatally an unusually thick umbilical cord with a yellow fluid filled cyst at the base was noted. The fluid from the cyst was confirmed as urine and ultrasound confirmed patent urachus. The baby underwent a cystoscopy and excision of patent urachus with associated allantoic cyst. Allantoic cyst is a rare swelling formed at the base of umbilicus associated with a patent urachus which results from an allantoic remnant. Paediatricians need to be aware about this condition as investigation is required to differentiate allantois cysts from umbilical pseudocysts. A patent urachus with allantoic cyst requires surgical excision.