Diagnostic accuracy of pre-procedural doppler ultrasound versus intra-procedural fluoroscopy in predicting successful percutaneous nephrostomy insertion in obstructive uropathy: A single-center experience

Background: Percutaneous nephrostomy (PCN) is a minimally invasive image-guided procedure for relieving urinary obstruction. While ultrasound and fluoroscopy are commonly used for guidance, the predictive value of pre-procedural Doppler ultrasound findings for procedural success remains incompletely characterized.
Objective: To evaluate the diagnostic accuracy of pre-procedural Doppler ultrasound parameters—specifically hydronephrosis grade, resistive index (RI), and calyceal dilatation—compared to intra-procedural fluoroscopic findings in predicting successful PCN insertion in patients with obstructive uropathy.
Methods: This retrospective cohort study included 168 patients who underwent PCN at Al-Bashir Hospital between January 2020 and December 2025. Pre-procedural Doppler ultrasound data (hydronephrosis grade per Society of Fetal Urology classification, interlobar artery RI, and pelvicalyceal diameter) and intra-procedural fluoroscopy data (contrast opacification quality, calyx visualization, and needle trajectory) were extracted from medical records. Technical success was defined as successful catheter placement with spontaneous urine drainage. Diagnostic accuracy was assessed using sensitivity, specificity, PPV, and NPV, with multivariate logistic regression to identify independent predictors of success.
Results: Among 168 patients (mean age 58.4±16.2 years, 56.5% male), PCN technical success was achieved in 92.9% (n=156). Hydronephrosis grade ≥3 demonstrated the highest sensitivity (94.2%) and NPV (96.4%). Doppler RI >0.70 had a specificity of 82.1% and PPV of 92.3%. On multivariate analysis, independent predictors of success were: hydronephrosis grade ≥3 (OR=4.82, 95% CI: 2.14–10.86), RI >0.70 (OR=3.45, 95% CI: 1.62–7.35), calyceal dilatation ≥8 mm (OR=2.98, 95% CI: 1.38–6.43), and good fluoroscopic opacification (OR=2.56, 95% CI: 1.18–5.56). Nondilated systems (SFU grade 0–1) had lower success rates (78.6% vs. 96.2%, p=0.001) and higher complication rates (32.1% vs. 14.4%, p=0.018). Combined ultrasound-fluoroscopy guidance was associated with higher success than either modality alone (96.8% vs. 86.4%, p=0.021).
Conclusion: Pre-procedural Doppler ultrasound parameters—particularly hydronephrosis grade ≥3 and RI >0.70—are strong predictors of PCN success, with comparable accuracy to intra-procedural fluoroscopy. These findings support a risk-stratified approach to PCN planning based on pre-procedural imaging.