Prenatal vesico-allantoic cyst outcome - a spectrum from patent urachus to bladder exstrophy.

Objective: The purpose of this study is to assess the prognostic significance of a cystic vesico-allantoic communication discovered on prenatal ultrasound in terms of its effect on the developing urinary tract.

Methods: Multi-institution review of prenatal screening ultrasound was performed between 2004 and 2015 to identify cases of in utero communication between the fetal urinary bladder and a cystic dilatation of the umbilical cord. Gestational age at diagnosis, perinatal evolution, and eventual urinary tract outcome are described and compared with existing literature.

Results: Five cases of cystic vesico-allantoic communication were identified on second-trimester screening ultrasound. Serial ultrasounds showed an increase in the size of the umbilical cystic component with gestational age, followed by its eventual rupture prior to delivery. All neonates had urinary leakage through the inferior portion of the umbilicus with bladder prolapse ranging from patent urachus to partial bladder exstrophy.

Conclusions: An isolated prenatal ultrasound finding of an hourglass communication between the fetal bladder and a cyst of the umbilical cord should be considered predictive of a spectrum from patent urachus to bladder exstrophy. Given the significant ramications on the developing urinary tract, the prenatal finding of vesico-allantoic cyst warrants referral to a high-risk obstetrical center with urologic consultation.