A retrospective analysis of ureteropelvic junction obstructions in patients with horseshoe kidney

BACKGROUND: Ureteropelvic junction obstruction (UPJO) is often encountered in patients with a horseshoe kidney (HSK) and may require surgical intervention. This study retrospectively investigated obstruction causes in HSK patients with UPJOs to determine the most suitable surgical method. METHODS: Twenty HSK patients with UPJO who underwent pyeloplasty between July 2000 and June 2020 and were followed-up for more than six months in our institution were included in the study. The clinical characteristics, obstruction causes, and surgical outcomes were analyzed. RESULTS: The median age at the time of the operation was 4.1 years [interquartile range (IQR): 1.8–10.6]. Hydronephrosis (HN) was found prenatally in 5 patients (25.0%). Pyeloplasty was performed by open, laparoscopic, and robotic techniques in 6, 10, and 4 patients, respectively. Sixteen patients (80.0%) had high ureteral insertion. Twelve patients (60.0%) had crossing vessels, and eight had a high ureteral insertion and crossing vessels. The median follow-up duration was 4.0 years (IQR: 1.8–8.9); no patient required additional surgery. The median differential renal function was 38.0% (IQR: 16.9–43.0%) preoperatively and 38.0% (IQR: 13.3–48.2%) postoperatively. CONCLUSIONS: UPJOs in HSKs were primarily caused by a high ureteral insertion and crossing vessels. Dismembered pyeloplasty was successfully performed in all surgical modalities such as the open, laparoscopic, and robotic approaches. Attention must be given to patients with HSKs, even in those without HN, to avoid UPJO development.