Hydronephrosis in pediatric horseshoe kidneys: a comparative analysis of open and laparoscopic pyeloplasty and the influence of obstruction causes

Background

Horseshoe kidney (HSK) represents a unique challenge for performing pyeloplasty due to its anomalous anatomy. Our study aimed to report our results in treating children with hydronephrosis in HSK and to investigate the differences in prognosis based on the cause of obstruction and the surgical approach. We also aimed to share our experiences by characterizing the success rates and complications after surgery.

Methods

We retrospectively reviewed the clinical data of hydronephrosis patients with HSK who were treated with pyeloplasty from August 2009 to June 2022. The patients were grouped according to different surgical methods and causes of obstruction, and then the clinical characteristics and outcomes were analyzed.

Results

Thirty-one patients were included in this retrospective cohort observational study, and surgical success was achieved in 80.6% (25/31) of patients. There was no significant difference in complications between open pyeloplasty (OP) and laparoscopic pyeloplasty (LP) groups (2/16 vs. 4/15, P=0.374). At 6 and 12 months postoperatively, both OP and LP groups experienced a decrease in anteroposterior pelvic diameter (APD) and the ratio of APD to the thickness of renal parenchyma (P/C ratio), accompanied by an increase in renal parenchymal thickness. Two patients of reobstruction were caused by missed crossing vessels in primary operation. The success rate of patients with crossing vessels (62.5%) was significantly lower than that of patients without crossing vessels (100%) (P=0.018).

Conclusions

Our study found that intrinsic obstruction, crossing vessels, and high insertion were the main causes of hydronephrosis in HSK, with missed crossing vessels being the primary cause of reobstruction. Our results demonstrate that both OP and LP are safe and effective in treating hydronephrosis in HSK patients.

Development of the prediction model for negative outcomes after primary laparoscopic pyeloplasty in children: a retrospective study of 535 patients

Background

Laparoscopic pyeloplasty (LP) has been widely accepted as an effective method to treat ureteropelvic junction obstruction (UPJO) in pediatric patients. Limited studies focused on the relationship between risk factors and negative outcomes. Our study aimed to seek independent risk factors for negative outcomes and construct a prognostic nomogram to assist clinical decision-making and improve outcomes.

Methods

A total of 535 patients with UPJO treated with primary LP between January 2016 and December 2020 were retrospectively reviewed. Negative outcomes were defined as restenosis requiring reoperation and grade III and IV complications based on the Clavien-Dindo grading system. Univariate and multivariate logistic regression analyses were used to select risk factors for negative outcomes after LP and developed the prediction model. The model was internally validated by the parametric bootstrapping method.

Results

Among the 535 patients, 33 (6.2%) developed negative outcomes. Ten patients developed ureteropelvic junction (UPJ) restenosis and underwent secondary surgery. UPJ leakage (two cases), difficulty of urinating after the removal of the Double-J (DJ) stent (two cases), and ileus (two cases) were the most common grade IIIa complications, while distal ureteral stricture (five cases), hernia formation (three cases), and delayed wound healing around the fistula (two cases) were the most common grade IIIb complications. After univariate and multivariate logistic analyses, the patient's weight, preoperative anteroposterior pelvic diameter (APD), and difficulty of DJ stent insertion were independent risk factors for negative outcomes, and they were used to fit the prediction model. The Brier score was 0.048. The model was relatively well-calibrated. The area under the receiver operating characteristic curve was 0.831 (95% CI: 0.756-0.906). Decision curve analysis illustrated good clinical utility.

Conclusions

Primary LP is a safe and effective method for pediatric patients with UPJO. The patient's weight, preoperative APD, and difficulty of DJ stent insertion were independent risk factors for negative outcomes after LP. We established and validated a predictive model for negative outcomes after LP. With the help of this model, clinicians can make better decisions and improve patient outcomes.