The effect of piezoelectric shock wave lithotripsy focus size on renal stones fragmentation: A prospective randomized study

Abstract

Background:In patients presenting with urolithiasis, shock wave lithotripsy (SWL) is an option in management. Aim of the work: The objective is to evaluate the efficacy of two different focal sizes of a piezoelectric extracorporeal lithotripter on renal stone fragmentation. Methods: The study was carried out on 150 patients with radio-opaque renal stones up to 20 mm seeking treatment by SWL. Patients were divided randomly into two equal groups. F1 focus = 2 mm, 126 MPa (Megapascal) was used for group A, and F2 focus = 4 mm, 119 MPa, was used for group B. After 3 months, KUB is done to determine the success of stone disintegration. Results: There were insignificant variations between the studied groups regarding loin pain, loin pain duration, stone size, stone sites, density, numbers, and hydronephrosis (p value > 0.05). The most frequent site of stones in group A and B was the mid calyx (29.5% and 33.3%, respectively). There were insignificant variations between the studied groups regarding residual after 3 months, size of residual, and successful stone disintegration rate (p value > 0.05). Regarding complications, colic was significantly higher in group B (22.7% vs. 9.3%, p = 0.026). Fever and hematuria were insignificantly different between the studied groups (p value > 0.05). Conclusion: Different focus sizes with fixed intensity and frequency result in non-significant differences concerning stone fragmentation. However, a combination of both F1 and F2 is recommended to achieve better results.