Adult duplex kidneys: an important differential diagnosis in patients with abdominal cysts

A 30-year-old-man who initially presented three years previously to the emergency department with right loin pain and a three-month history of haematuria. He reported no other urinary symptoms and was otherwise fit and well with no significant past medical history. Flexible cystoscopy was unremarkable and evaluation with ultrasound and a computed tomography (CT) scan demonstrated a large right-sided renal cyst (see Figure 1a), which was subsequently treated with laparoscopic marsupialization, draining 2.2 L. The patient was re-referred two years following this with recurrence of his right loin pain and a general feeling of discomfort. Investigation by a repeat CT scan revealed the presumed renal cyst was in fact a dilated non-functioning upper moiety and dilated ureter that traced downwards into the pelvis. The patient underwent excision of the non-functioning right upper pole moiety and megaureter using an open approach. Prior to incision the patient underwent cystoscopy and stenting of the lower pole normal ureter. A subcostal incision was used with retroperitoneal mobilization of the kidney and upper dilated segment. The cystic segment was opened and drained 2 L of cloudy urine. The dilated upper pole segment was then excised (see Figure 2). An oblique incision in the right iliac fossa was used for retroperitoneal mobilization of the grossly dilated ureter. As the dilated upper ureter ran close to the lower pole ureter, the distal end of the dilated ureter was divided to excise the ureter, leaving a ureteral stump. The postoperative period was uneventful and the patient was discharged home within five days. The stent in the lower pole ureter was removed endoscopically at routine follow-up and the patient has remained well.