“Duplex sans duplex: a cryptic cause”: a case report

Abstract Background Duplex kidneys represent an embryologic maldevelopment at time of renogenesis resulting in a spectrum of bifurcation anomalies of the reno-ureteric system. Though most are antenatally detected, recurrent urinary tract infections (UTIs), abdominal mass due to obstruction and incontinence are other common manifestations. Upper moiety ureter is usually obstructed and the lower moiety is refluxing. Management is guided by the percentage function of each of the moieties. A non-functioning system warrants a heminephrectomy. We report a toddler with right flank mass and a provisional diagnosis of right duplex system following investigations but met with a cryptic cause at surgery thereby altering the management. Case presentation A 2 ½ years girl with progressively increasing right abdominal mass for 6 weeks was found to have 12 × 10 cm right non-tender flank mass. Ultrasonography, contrast tomography and nuclear scans showed a right duplex system with obstructed, poorly functioning lower moiety. A lower moiety heminephrectomy was planned but at surgery, a densely adherent cystic structure displacing the right kidney superiorly was noted. On decompressing, the ureter was found to enter the cyst with discontinuation for a length of 6cms before being traced distally to its entry into the bladder. Retrograde pyelogram confirmed mid-ureteral transection and cystic urinoma. The cyst was excised and the ureter reconstructed with an appendicular interposition graft. Child recovered uneventfully and at 8 months follow up is well with good drainage across the conduit. Conclusion The case highlights a rare presentation of mid-ureteral transection with urinoma masquerading as a duplex system and its satisfactory management.