Renal Stone Features Are More Important Than Renal Anatomy to Predict Shock Wave Lithotripsy Outcomes: Results from a Prospective Study with CT Follow-Up

Abstract

Introduction: Lower pole kidney stones have been associated with poor shock wave lithotripsy (SWL) outcomes because of its location. However, the real impact of collecting system anatomy on stone clearance after SWL is uncertain. There is a lack of prospective well-controlled studies to determine whether lower pole kidney stones have inferior outcomes than nonlower pole kidney stones when treated with SWL. Methods: We prospectively evaluated patients with a single kidney stone of 5-15 mm undergoing SWL from June 12 through January 19. All patients were subjected to computed tomography before and 3 months after the procedure. Demographic data (age, gender, and body mass index), stone features (stone size, stone area, stone density, and stone-skin distance-SSD), and collecting system anatomy (infundibular length and width, and infundibulopelvic angle) were recorded. Outcomes (fragmentation and stone clearance rates) were compared between lower pole and nonlower pole cases. Then, a multivariate analysis including all variables was performed to determinate which parameters significantly impact on SWL outcomes. Results: One hundred and twenty patients were included in the study. Mean stone size was 8.3 mm and mean stone density was 805 Hounsfield units. Overall stone fragmentation, success, and stone-free rates were 84.1%, 64.1%, and 34.1%, respectively. There were no significant differences in stone fragmentation (76.0% vs 71.4%; p = 0.624), success rate (57.6% vs 53.3%; p = 0.435), and stone-free rate (40.2% vs 35.7%; p = 0.422) in the lower vs nonlower pole groups, respectively. On multivariate analysis, only stone density (p < 0.001) and SSD (p = 0.006) significantly influenced fragmentation. Stone size (p = 0.029), stone density (p = 0.002), and SSD (p = 0.049) significantly influenced kidney stone clearance. Conclusions: Stone size, stone density, and SSD impact on SWL outcomes. Lower pole kidney stones have similar fragmentation and stone clearance compared with nonlower pole kidney stones.

Residual Stone Fragments After Percutaneous Nephrolithotomy: Shockwave Lithotripsy vs Retrograde Intrarenal Surgery

“…At the very best, SFRs were at the bottom end of the range of previous reports of first-line SWL or RIRS. [9][10][11]24,25 Some of the explanation for that is we report SFR mainly based on NCCT (81.8% of the SWL group and 100% of the RIRS group), whereas other reports were based mainly on ultrasound plus KUB. 26 Other possible explanation is that standard PCNL may alter normal collecting system anatomy and influence SFR of a second-line therapy.…”

“…Patients were discharged 2 hours after the end of the procedure if VAS for pain was >3 with oral analgesics for 7 days and alpha-blockers for 30 days. 11 SFR defined as no stone fragments and success rate defined as £2 mm were evaluated on POD 90 by NCCT or ultrasound and kidney, ureter, and bladder radiograph (KUB) for each renal unit. 16 Surgical complications based on Clavien-Dindo classification during the 90 days of follow-up were recorded.…”

“…Although SFR of SWL for kidney stones up to 20 mm evaluated by NCCT ranges from 35% to 40%, it is less invasive and it is another option to treat RSFs after PCNL. 11 The aim of this study was to compare the outcomes of RIRS to SWL for treating patients with RSFs after a previous standard PCNL.…”

Treatment of renal lower pole stones: an update

“…SWL stone-free rates are more influenced by stone burden and composition and by patient's body habitus, overall obesity as well as renal anatomy as previously stated (38). Many studies comparing the results of SWL, FURS and PCNL have been published and some of them are summarized in Table-2 (39)(40)(41)(42)(43)(44)(45)(46)(47).…”

Development of a novel predictive model for a successful stone removal after flexible ureteroscopic lithotripsy based on ipsilateral renal function: a single-centre, retrospective cohort study in China

“… 15 17 18 A recent prospective study with CT follow-up also reported that renal stone features are more critical than renal anatomy in predicting the outcomes of shockwave lithotripsy. 19 …”