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

Abstract

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.

Antenatal Workup of Early Megacystis and Selection of Candidates for Fetal Therapy

“…In our cohort, we found a UCC in 12% (29/233) of fetuses with early megacystis. Previous studies have suggested that UCC may be an early sign of severe obstructive uropathy [24,25]. This study is the first to clearly indicate that evidence of a UCC in DOI: 10.1159/000488282 conjunction with a megacystis is a strong marker of urethral atresia, already from the first trimester of pregnancy.…”

“…A plausible explanation for the association between megacystis and urethral atresia is that during the first stages of life, the bladder is connected with the umbilical cord through the allantois, which obliterates at 6-12 weeks' gestation to form the urachus, a fibromuscular tubular structure located between the apex of the bladder and the umbilical cord insertion. An abnormally distended urinary bladder could prevent the closure of the allantois and eventually lead to a cystic dilatation of the allantois or of the umbilical cord [25,26]. This is more likely to occur in fetuses with an early and severe bladder enlargement, as it is the case in the setting of urethral atresia.…”

Prenatal ultrasound findings of covered bladder exstrophy and persistent cloaca

“…These anomalies can present with an isolated abdominal midline cystic mass with an hour-glassing connection to the bladder without pubic separation and typically disappear with advancing pregnancy. 10 Other pathologies in the differential include pseudo exstrophy, omphalocele, and cloacal exstrophy (CE). Pseudo exstrophy is another BE variant with divergent abdominal wall muscle, separated symphysis pubis, and genital defects but with an intact anterior bladder wall covered with skin.…”

Fetal cloacal dysgenesis sequence presented with first trimester megacystis and associated umbilical cord abnormalities

“…The presence of umbilical cord cyst has been reported at the first trimester scan in 0.4–3.4% of fetuses and in 12% of fetuses with early megacystis. The simultaneous occurrence of megacystis and umbilical cord cyst in the first trimester scan is a strong early sign of severe obstructive uropathy, namely urethral atresia . In the case of lower urinary tract obstruction, increased intravesical pressure may not let allantois obliterate, rather it reflects in a retrograde way.…”

“…The simultaneous occurrence of megacystis and umbilical cord cyst in the first trimester scan is a strong early sign of severe obstructive uropathy, namely urethral atresia. 6,7,13 In the case of lower urinary tract obstruction, increased intravesical pressure may not let allantois obliterate, rather it reflects in a retrograde way. The leakage of urine backwards into the umbilical cord can result in the formation of an allantoic cyst or rarely, in transudation of hypoosmotic urine into the Wharton jelly, leading to massively enlarged umbilical cord.…”