The effect of piezo-lithotripsy with 2-and 8-mm focus sizes on stone disintegration and renal injury.

Abstract

To compare the efficacy and safety of shock-wave lithotripsy (SWL) using a narrow-focus and wide-focus for renal stones. A double-blind randomized trial included adult patients with solitary radio-opaque renal pelvic stone 1-2 cm. Patients were randomized into two groups; narrow-focus (2 mm) SWL and wide-focus (8mm) SWL. The stone-free rate (SFR) and presence of complications such as hematuria, fever, pain, and peri-renal hematoma were evaluated. Preoperative and postoperative urinary markers (NGAL and KIM-1) levels were compared to assess the renal injury. A total of 135 patients were recruited for this study. The SFR after the first SWL session was 79.2% and 69.1% in narrow- and wide-focus groups, respectively. There was a comparable rise in the median (IQR) 2-hour NGAL level in both groups (p= 0.62). However, the rise in the median (IQR) 2-hour KIM-1 level was significantly higher in the narrow-focus 4.9 (4.6, 5.8) ng/mL compared with the wide-focus group 4.4 (3.2, 5.7) ng/mL; (p=0.02). Nevertheless, 3-day urinary markers were significantly improved in NGAL and in KIM-1 (p= 0.263 and 0.963), respectively. The overall SFR after three sessions was 86.6% and 86.8% in narrow- and wide-focus groups, respectively (p=0.77). Both groups were comparable in complications, apart from the median (IQR) pain score and the percentage of high-grade hematuria which were significantly higher in the narrow-focus group (p<0.001and p=0.03), respectively. Narrow-focus and wide-focus SWL were associated with comparable outcomes and re-treatment rates. However, narrow-focus lithotripsy was associated with significantly higher morbidity in terms of pain and hematuria.