Horseshoe kidney is the most common congenital renal fusion anomaly, occurring in approximately 0.1–0.25% of births. Although often asymptomatic, individuals with this anomaly have a reported incidence of ureteropelvic junction obstruction (UPJO). However, data on the management of UPJO in horseshoe kidneys remain limited. Here, we present a case of a symptomatic horseshoe kidney with left UPJO and discuss the subsequent clinical outcomes.

A 27-year-old female presented with intermittent left flank pain for two years. She denied any history of trauma, urolithiasis, dysuria, or hematuria. Thorough exam demonstrated a horseshoe kidney with left UPJO complicated with severe hydronephrosis. The patient underwent robotic-assisted laparoscopic transperitoneal left dismembered pyeloplasty. Intraoperatively, a dilated renal pelvis with high ureteral insertion was observed, along with an external compression of the upper left ureter by an aberrant renal artery. The surgical procedure involved excision of the stenotic UPJ segment, transposition of the aberrant artery, and ureteropelvic anastomosis. The patient was followed for three months, during which significant clinical improvement was observed.

UPJO in horseshoe kidneys is believed to arise from congenital strictures at the UPJ, high ureteral insertion, abnormal ureteral course over the isthmus, external compression by crossing vessels, or abnormal UPJ motility. Hydronephrosis occurs in approximately 14–35% of affected individuals, with symptoms often resulting from urinary obstruction, infection, or stone formation. This case highlights the advantages of robotic-assisted laparoscopic pyeloplasty in managing UPJO in horseshoe kidneys. Compared to conventional open or laparoscopic pyeloplasty, robotic surgery provides superior dexterity, precision, and visualization, especially in anatomically challenging cases such as horseshoe kidney with aberrant vasculature.

Rare cases of horseshoe kidney with UPJO complicated with severe hydronephrosis are reported so far. We present this case to share our experience of diagnosis and management of such peculiar condition, underwent surgical intervention and further treatment at Taipei Cathay General Hospital.