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

Abstract

To compare the efficacy and safety of shockwave lithotripsy (SWL) using a narrow focus or wide focus for renal stones. A double-blind randomised trial included adult patients with a solitary radio-opaque renal pelvic stone of 1-2 cm. Patients were randomised into two groups: narrow-focus (2 mm) SWL and wide-focus (8 mm) SWL. The stone-free rate (SFR) and presence of complications such as haematuria, fever, pain, and peri-renal haematoma were evaluated. Pre- and postoperative urinary markers (neutrophil gelatinase-associated lipocalin [NGAL] and kidney injury molecule 1 [KIM-1]) concentrations were compared to assess 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 2-h NGAL concentration in both groups (P = 0.62). However, the rise in the median (interquartile range [IQR]) 2-h KIM-1 concentration was significantly higher in the narrow-focus group at 4.9 (4.6, 5.8) ng/mL compared with the wide-focus group at 4.4 (3.2, 5.7) ng/mL (P = 0.02). Nevertheless, the 3-day NGAL and KIM-1 urinary marker concentrations were significantly improved (P = 0.263 and P = 0.963, respectively). The overall SFR after three sessions was 86.6% and 86.8% in the narrow- and wide-focus groups, respectively (P = 0.77). Both groups were comparable for complications, apart from the median pain score and the percentage of high-grade haematuria, which were significantly higher in the narrow-focus group (P < 0.001 and P = 0.03, respectively). Narrow- and wide-focus SWL were associated with comparable outcomes and re-treatment rates. However, narrow-focus SWL was associated with significantly higher morbidity in terms of pain and haematuria.