Factors Associated with a Higher Risk of Conversion from Radiation-Free Percutaneous Nephrolithotomy (PCNL) to Fluoroscopy-Guided Percutaneous Nephrolithotomy

Abstract

Introduction and Objective:

Percutaneous nephrolithotomy percutaneous nephrostomy (PCNL) is a minimally invasive procedure for kidney stone removal traditionally guided by fluoroscopy. This study aimed to evaluate the feasibility and outcomes of radiation-free PCNL using ultrasonography alone compared with standard fluoroscopy-guided PCNL.

Methods:

A total of 63 PCNL cases were eligible for radiation-free PCNL, but 27 were excluded (intraoperatively aborted, ureteroscopy performed instead, preoperative complex anatomy). Of the remaining 36 cases eligible for radiation-free PCNL, 11 were converted intraoperatively to fluoroscopic-based PCNL. Postoperative computed tomography (CT) imaging was available for only 16 of the 25 radiation-free PCNL cases and 4 of the 11 converted cases. We designated these 16 prospective radiation-free PCNL cases (2024–2025) as Group A. For comparison purposes, we identified a historical case-matched cohort of 150 PCNLs. Of these, 67 were excluded (similar reasons), leaving 83 retrospective fluoroscopy-guided PCNL cases (2022–2024) called Group B. A subset of Group A cases was converted from radiation-free intraoperatively to fluoroscopy and were designated as Group C. The primary outcome was stone-free rate (SFR), assessed postoperatively by noncontrast CT (2–3 mm slices). Secondary outcomes included estimated blood loss, complication rates (Clavien–Dindo), and postoperative stone events.

Results:

The median preoperative stone burden was 35 mm in Group A and 27 mm in Groups B and C [p = 0.3]. SFR (Grade A) was comparable across Groups A, B, and C [38%, 30%, and 25%, respectively (p = 0.8)]. No differences were observed in complications or secondary outcomes.

Conclusions:

Radiation-free PCNL is feasible and yields comparable outcomes to standard fluoroscopy-guided PCNL, offering a promising method to reduce radiation exposure without compromising surgical success. However, we identified a consistent theme of poor visualization that prompted conversion to fluoroscopy for some of the cases. Innovation directed toward improving tool echogenicity is key to diffusing this technique.