Incomplete duplication of the collecting system is a condition in which there is a partial or incomplete duplication of the renal collecting ducts or renal pelvis in the kidneys. Incomplete duplication of the collecting system can lead to a variety of complications, though many people with this condition may be asymptomatic. We herein present a case of a 42-year-old male suffered from incomplete duplication of the left collecting system complicated with ureteral stone.

The patient presented to the urology outpatient clinic with persistent left ureteral stone and renal colic. Urinalysis showed RBCs at 10-19/HPF. An abdominal CT scan revealed a 1 cm ureteral stone located in the left proximal ureter. Despite an attempt at extracorporeal shock wave lithotripsy, the stone remained in place. Subsequently, retrograde intrarenal surgery with flexible ureteroscopy was performed. During the procedure, incomplete duplication of the collecting system was identified, with the ureteral stone impacted in the upper moiety. Lithotripsy was carried out using a holmium laser, and a double J catheter was inserted into the collecting system. Postoperative imaging showed a stable double J catheter in the left collecting system

Ureteral duplication is most common in females and may be incomplete or complete. Complications of incomplete duplication is most often associated with ureteroureteral reflux or ureteropelvic junction obstruction of the lower pole of the kidney, which may also be associated with urinary stones. Incomplete duplication of collecting system may be difficult to detect preoperatively. During endoscopic surgeries, the lesions such as urinary stones or tumors may easily be neglected. Therefore, preoperative image study such as CT urography is helpful for diagnosis.

Incomplete duplication of the collecting system presents a diagnostic challenge, especially during endoscopic procedures, highlighting the importance of thorough preoperative imaging to avoid overlooking critical issues like urinary stones or tumors.