Shockwave lithotripsy: techniques for improving outcomes
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.