Intraoperative Cone Beam Computed Tomography Increases Single Procedure Stone-Free Rates in Percutaneous Nephrolithotomy: Results of a Randomized Controlled Trial

Introduction: Achieving a stone-free status during percutaneous nephrolithotomy (PCNL) is crucial to prevent additional morbidity or stone growth. Cone beam computed tomography (CBCT) in a hybrid operating room provides intraoperative imaging of the urinary tract, improving stone-free status assessment and enabling additional stone extraction. This study aimed to determine whether intraoperative CBCT leads to increased stone-free rates (SFR) after PCNL.

Materials and Methods: We conducted a two-arm randomized trial involving adult patients undergoing PCNL at a tertiary referral center for complex kidney stone treatment. Intraoperative randomization took place when the kidney was deemed endoscopically stone free. Patients were assigned to either undergo an intraoperative CBCT scan or be placed in a control group, in which the procedure was ended without a CBCT scan. All patients underwent a low-dose noncontrast abdominal CT scan 4 weeks postoperatively. The primary outcome measure was the stone-free status evaluated by this scan.

Results: This trial was prematurely terminated because of reaching the predefined criteria for superiority upon interim analysis, with 160 randomizations up to this point. SFR was 15% higher in the CBCT group (76% vs 61%, p = 0.04) using a 4-mm cut-off. With a 2-mm cut-off, the SFR difference was 14% (58% vs 44%, p = 0.08). Using a 0-mm cut-off, the difference was 9% (50% vs 41%, p = 0.27). Residual fragments were identified in 56% of CBCT scans, with additional extraction in 49% of these cases. No significant difference in 30-day postoperative complications was observed.

Conclusion: Intraoperative CBCT during PCNL significantly increases single procedure SFR.

Trial registration: Netherlands Trial Register (NTR) NL8168, ABR NL70728.042.19. Prospectively registered on 15 October 2019.