An exceptionally rare cause of fetal megacystis in a male fetus

Abstract

Megacystis in a male fetus is most commonly due to posterior urethral valves (PUV). Reported incidence ranges from 1:5000–1:8000 births. Other causes of megacystis in a male fetus include prune belly syndrome, neurogenic bladder, bilateral high grade V-U reflux etc. We are presenting a case of megacystis diagnosed at 27 weeks gestation, due to large tortuous ectopic ureter from a single system inserting into the prostatic urethra. This case highlights the interesting diagnostic and management challenges encountered with an exceptionally rare malformation causing bladder outlet obstruction. The antenatal ultrasound at 20 week gestation was normal. By 33 weeks, bilateral pelvicalyceal dilatation and bilateral hydroureter was seen; additionally, bladder appear enlarged. Ultrasound at 39 week gestation suspected the right ureteric insertion to be ectopic into the bladder neck. Follow up scans demonstrated worsening hydroureteronephrosis and megacystis. The amniotic fluid volume remained within normal limits. Working diagnosis was bladder outlet obstruction due to PUV. His post-natal ultrasounds, MCUG and MRU confirmed a single system on the right side with ectopic insertion into the prostatic urethra causing bladder outlet obstruction. On the left a low lying malrotated kidney & grade 4-5 vesicoureteric reflux was noted. Serum creatinine was high in the neonatal period. He underwent cystoscopy to confirm the ectopic right ureteric insertion. The right ureter was disconnected from prostatic urethra and an end cutaneous ureterostomy was performed to relieving bladder outlet obstruction and allowing better decompression of right ureter. At 9 months follow-up his renal function had normalized and he had a good urinary stream. The right ureter will be re-implanted to the bladder at 2 years of age. There are few similar cases of similar cases of megacystis in the literature. Ectopic ureters inserting into posterior urethra causing bladder outlet obstruction in all case reports are diagnostic conundrum and must be considered as rarer differential diagnoses to PUV.