Urologists are optimistic surgeons: prevalence and predictors of discordance between intraoperative stone-free rate and cross-sectional imaging evaluation after vacuum-assisted mini-percutaneous nephrolithotomy

Abstract

Purpose To assess how accurate are urologists in predicting stone-free status (SFS) after vacuum-assisted mini-PCNL (vamPCNL) compared to computed tomography (CT) and clinical predictors of discordant SFS. Methods Data from 235 patients who underwent vamPCNL were analysed. Patient’s demographics, stones’ characteristics and operative data were recorded. SFS was evaluated intraoperatively by the treating urologist (iSFS) and with non-contrast CT 3 months after vamPCNL (ctSFS). SFS was defined as no residual stones. Stone complexity was scored with the Guy’s score. Descriptive statistics and logistic regression models were used to identify clinical factors associated with discordant SFS (namely iSFS not confirmed at CT). Results iSFS and ctSFS were 88.5% and 65.5%, respectively, with 54 (23%) cases resulting in discordant evaluation of SFS between the surgeon and CT imaging. Patients with discordant SFS had larger stone volume (p < 0.001), higher rate of multiple stones (p = 0.03) and higher rate of multiple calyceal groups affected by stones (p < 0.001) than those with concordant SFS. The use of flexible ureteroscopes to look for residual stones after lithotripsy was more frequently reported in cases with concordant SFS (p = 0.001). Multivariable logistic regression analysis revealed that stones in > 2 calyceal groups (OR 10.2, p < 0.001), Guy’s score II (OR 5.8, p < 0.01) and not using flexible ureteroscopes after lithotripsy (OR 2.9, p = 0.02) were independent predictors of discordant SFS. Conclusion One out of five patients is erroneously considered SF after vamPCNL. Urologist should carefully evaluate patients with multiple calyceal stones and consider using flexible ureteroscopes to complete lapaxy of migrated fragments in order to improve their prediction of SFS.

Comparison of endoscopic versus CT assessment of stone-free status after percutaneous nephrolithotomy (PCNL)

“…1). Patient's characteristics, as well as intraoperative and postoperative patient ´s cohort parameters, are presented in Table between intraoperative SFS and CT-based SFS was determined after vacuum-assisted PCNL [13]. In this study the surgeon was able to accurately predict SFS in 77% of cases.…”

Comparison of endoscopic versus CT assessment of stone-free status after percutaneous nephrolithotomy (PCNL)

“…The NPV of the surgeon’s assessment for SFS was 100% (sensitivity: 100%, specificity: 12.5%, PPV: 75%) [ 14 ]. In another study, conducted by Jannello et al in 2022, the match rate between intraoperative SFS and CT-based SFS was determined after vacuum-assisted PCNL [ 13 ]. In this study the surgeon was able to accurately predict SFS in 77% of cases.…”

“…Compared to KUB and sonography, LDCT might expose patients to higher doses of radiation but can be performed quickly, does not require contrast agent administration, and detects RF of all sizes with high sensitivity [ 11 , 12 ]. Only few studies have investigated the correlation between intraoperative SFS defined by the surgeon compared with postoperative LDCT [ 13 , 14 ].…”

Transient ureteral obstruction after mini-percutaneous nephrolithotomy is associated with stone volume and location: results from a single-center, real-life study

“…Postoperative complications were graded according to the PCNL-adjusted Clavien score [ 16 , 17 ]. Patients were evaluated within 3 months after surgery with non-contrast-enhanced CT scan to identify residual stones [ 18 ]. Procedures were defined as stone-free if no residual stones were detected.…”