Can intraoperative endoscopic evaluation replace postoperative low-dose CT for assessing the stone-free status in vacuum-assisted dedusting lithotripsy.

Abstract

Purpose: To compare the diagnostic accuracy of intraoperative endoscopic assessment with postoperative low-dose computed tomography (LDCT) for determining stone-free status (SFS) following retrograde vacuum-assisted dedusting lithotripsy (VADL) using a tip-flexible vacuum-assisted suction ureteral access sheath (tFVS-UAS) and evaluate the feasibility of replacing routine LDCT with intraoperative evaluation.

Methods: This single-center retrospective study analyzed 1,105 patients undergoing unilateral VADL (December 2022-December 2024). All VADL procedures were performed retrograde using tFVS-UAS. Postoperative LDCT on day 30 served as the reference standard. Agreement between intraoperative endoscopic assessment and LDCT was evaluated using McNemar's test and Kappa statistics. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

Results: The overall stone-free rate (SFR) was 83.35% (89.89% for stones ≤ 20 mm; 63.50% for stones > 20 mm). Intraoperative assessment demonstrated high specificity (98.70%, 95% CI: 97.80-99.60%) but low sensitivity (43.48%, 95% CI: 36.35-50.61%), with an NPV of 89.73% and PPV of 86.96%. Subgroup analysis revealed stronger agreement for stones ≤ 20 mm (Kappa = 0.61, NPV = 94.40%) compared to stones > 20 mm (Kappa = 0.40, sensitivity = 40.00%)(Bonferroni-adjusted α = 0.025).

Conclusion: Intraoperative endoscopic assessment during VADL reliably confirms SFS for stones ≤ 20 mm, potentially reducing the utilization of postoperative LDCT in low-risk patients when SFS is endoscopically verified. However, LDCT remains essential for stones > 20 mm or high-risk scenarios due to limited sensitivity. Clinical implementation requires risk stratification and shared decision-making.