Factors affecting Infectious Complication following Flexible URS in Zanco Private Hospital

Abstract

Background: Flexible ureteroscopy (f-URS) has emerged as the gold standard for treating renal stones <2 cm, offering excellent stone-free rates (85-95%) with minimal invasiveness. However, infectious complications remain a significant clinical concern with reported incidence rates varying from 10-25% across different populations. Understanding modifiable and non-modifiable risk factors is paramount for optimizing patient outcomes, developing targeted prevention strategies, and improving the overall safety profile of endoscopic stone surgery in contemporary urological practice.

Objective: To prospectively identify, quantify, and validate preoperative, intraoperative, and postoperative risk factors associated with infectious complications following f-URS; develop a clinically applicable predictive model for evidence-based risk stratification; and propose comprehensive prevention and management strategies for high-risk patients based on robust statistical modeling and contemporary clinical evidence.

Methods: Single-center prospective cohort study at Zanco Private Hospital, Erbil, Iraq (October 2020-October 2021). Fifty consecutive patients undergoing f-URS for renal stones were enrolled using strict inclusion/exclusion criteria. Comprehensive data collection included patient demographics, medical comorbidities, preoperative laboratory assessments, stone characteristics via high-resolution CT imaging, operative parameters, and systematic 14-day postoperative surveillance. Infectious complications were defined as fever >38.5°C for >24 hours, SIRS, sepsis, or septic shock. Advanced statistical analysis employed univariate screening, multivariate logistic regression with bootstrap validation, and comprehensive model performance assessment.

Results: Infectious complications occurred in 11/50 patients (22%, 95% CI: 11.5-36.0%). Multivariate analysis identified four independent risk factors: preoperative pyuria >5 WBC/hpf (aOR 8.42, 95% CI 2.08-33.72, p=0.003), age <40 years (aOR 5.18, 95% CI 1.24-22.14, p=0.026), operative time >70 minutes (aOR 4.83, 95% CI 1.11-20.92, p=0.037), and incomplete stone clearance (aOR 3.91, 95% CI 1.02-15.21, p=0.048). The predictive model showed excellent discrimination (AUC 0.84, 95% CI 0.73-0.95) and good calibration (Hosmer-Lemeshow p=0.612). Risk stratification: low-risk (0-1 factors, 5.6%), moderate-risk (2 factors, 25.0%), high-risk (3-4 factors, 60.0%).

Conclusions: Preoperative pyuria, younger age, prolonged operative time, and incomplete stone clearance independently predict infectious complications following f-URS. The validated model enables evidence-based risk stratification supporting personalized prevention protocols including mandatory preoperative urinalysis optimization, enhanced surveillance for high-risk patients, surgical technique refinement to minimize operative duration, and systematic strategies to maximize stone clearance rates.