Shockwave Lithotripsy Is an Efficacious Treatment Modality for Obese Patients with Upper Ureteral Calculi: Logistic Regression and Matched-Pair Analyses from a Dedicated Center Comparing Treatment Outcomes by Skin-to-Stone Distance.

Objectives: To assess the association of skin-to-stone distance (SSD) and stone-free rates following extracorporeal shockwave lithotripsy (SWL) using two statistical methods: logistic regression and a matched-pair analysis approach. Patients and Methods: Patients with a solitary radio-opaque upper ureteral calculus diagnosed on noncontrast computed tomography were included. Patients were treated with a Sonolith I-Sys Lithotripter (focal depth 17 cm). Stone treatment success was defined as stone free (fragments ≤3 mm) at 3 months. Failure was defined as persistent fragments beyond 3 months or requirement for intervention with ureteroscopy. The outcome was assessed by a plain kidney, ureter, and bladder radiograph (KUB) at 2 weeks. Logistic regression was used to determine association of patient and stone factors with treatment failure. The patient cohort was divided into tertiles by SSD, and matched-pair analysis was undertaken between individuals from the top and bottom tertiles (SSD ≤12 cm and SSD ≥14 cm). Matching criteria consisted of age, sex, maximum stone diameter (±2 mm), and stone density (±250 HU). Results: From a database of 2849 patients who underwent SWL, 397 patients were identified who had treatment of a single upper ureteral stone. Age (odds ratio [OR]: 1.03, 95% confidence interval [CI]: 1.01-1.04, p = 0.007), SSD (OR: 1.16, 95% CI: 1.03-1.32, p = 0.02), stone side (OR: 1.65, 95% CI 1.01-2.73, p = 0.05), stone diameter (OR: 1.09, 95% CI: 1.00-1.19, p = 0.05), and multiple sessions (OR: 4.65, 95% CI: 2.61-8.29, p < 0.001) were significantly associated with treatment failure by logistic regression univariable analysis. Multiple sessions was the only factor significantly associated with treatment failure on multivariable analysis (OR: 4.03, 95% CI: 2.18-7.42, p < 0.001). From a cohort of 141 patients with SSD ≥14 cm and 174 patients with a SSD ≤12 cm, 66 matches were identified (132 patients). Forty-nine patients (74.2%) with SSD ≥14 cm were deemed stone free at follow-up vs 51 patients (77.3%) with SSD ≤12 cm (p = 0.85). Conclusion: This study demonstrates by two statistical methods that SWL can provide efficacious treatment of upper ureteral stones in obese patients and that the upper threshold of SSD for SWL with Sonolith I-SYS could be revised to allow these patients the benefits of SWL.

Extracorporeal shockwave lithotripsy to distal ureteric stones: the transgluteal approach significantly increases stone-free rates.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Shockwave lithotripsy (SWL) can be used to treat stones at any position within the ureter, as long as the stone is radio-opaque and there is a path for the shockwave to reach the stone. However the results of SWL to distal ureteric calculi, with the patient in a prone position, were inferior to those of treating stones within the upper ureter. The transguteal approach allows the lithotripsy shockwave to reach the lower ureter via the greater selatle foramen. This study shows that this approach for SWL to distal ureteric calculi is more effective than the prone approach. OBJECTIVE: To compare the outcomes of extracorporeal shockwave lithotripsy (ESWL) for distal ureteric stones treated using the prone and transgluteal (supine) approaches in a tertiary referral stone unit using a fourth generation lithotriptor. PATIENTS AND METHODS: We selected consecutive patients undergoing ESWL to distal ureteric stones over 1 year, during which we changed our treatment protocol from a prone to transgluteal (supine) approach. Patients were treated using the Sonolith Vision Lithotriptor (Technomed Medical Systems, Vaulx-en-Velin, France). Outcome was assessed using plain abdominal film of kidney, ureter and bladder (KUB) X-ray taken at 2 weeks then monthly as required. Treatment success was defined as complete clearance of stone fragments and treatment failure was defined as persistence of stone fragments beyond 3 months or the need for ureteroscopy. RESULTS: A total of 38 patients were treated in the prone position and 72 patients using a transgluteal approach. Patient and stone characteristics were identical in both groups. The mean (range) stone size was 7.8 (4-16) mm. The proportions of patients who were stone-free after one treatment session within the prone and transgluteal treatment groups were 40 and 78%, respectively (<0.001). The overall success rates for treatment within the prone and transgluteal groups were 63 and 92%, respectively (<0.001). CONCLUSIONS: Transgluteal ESWL to stones within the distal ureter leads to significantly higher stone-free rates than treatment using the prone approach. The majority of patients are rendered stone-free after one session of treatment and the overall success rates are similar to those of ureteroscopic management.