Chung VY et al, 2016: The success of shock wave lithotripsy (SWL) in treating moderate-sized (10-20 mm) renal stones.
Chung VY, Turney BW.
Oxford Stone Group, Department of Urology, Churchill Hospital, Nuffield Department of Surgical Sciences, University of Oxford, Headington, Oxford.
Abstract
Many centres favour endourological management over shock wave lithotripsy (SWL) in the management of moderate-sized (10-20 mm) renal stones. International guidelines support all available modalities for the treatment of these stones. The aim of this study was to evaluate the efficacy of SWL in the treatment of 10- to 20-mm renal stones. From January 2013 to October 2014, all patients with a renal stone measuring between 10 and 20 mm in maximum diameter on CT scan that were eligible for lithotripsy were included. 130 consecutive patients were evaluated. Demographics, location of stone within the kidney, number of SWL sessions and treatment outcomes were analysed. Treatment success was classified into complete stone clearance and the presence of clinically insignificant residual fragments <4 mm (CIRF). 119 patients (92 %) completed treatment and radiological follow-up. Eleven patients were excluded due to incomplete follow-up data. The mean age was 56.8 (23-88). Male to female ratio was 1.9:1 (78:41) and the mean BMI was 28.4 (17.9-58). The mean stone size was 12.8 mm (10-14 mm: n = 87; 15-20 mm: n = 32). The mean number of treatments was 2.14 and 2.82 for stones 10-14 and 15-20 mm, respectively. Overall treatment success was 66.4 % (combined complete stone clearance and CIRFs). Subdivided by stone size <15 mm and ≥15 mm, the success rate was 70.4 and 53.1 %, respectively. The treatment success by stone location was 65, 64 and 70 % for upper, middle and lower pole stones, respectively and 67 % for PUJ stones. For those who failed SWL treatment, the majority 50 % (n = 20) were managed expectantly, 42.5 % (n = 17) required URS, and 7.5 % (n = 3) required PNL. This study suggests that SWL has an efficacy for treating larger renal stones (10-20 mm) that is equivalent to success rates for smaller stones in other series. As a low-risk and non-invasive procedure SWL should be considered a first-line treatment for these stones.
Urolithiasis. 2016 Jan 7. [Epub ahead of print]
Comments 1
As the authors state it is a good rule to balance the aim of the stone treatment with the efforts necessary to achieve the goal. The obvious advantages of SWL are emphasized: a non-invasive treatment modality not requiring anaesthesia and possible to complete in an out-patient setting. SWL also have a low rate of complications.
In view of the current enthusiasm for endo-urological procedures (without most of the benefits listed above) the authors analysed the results of SWL in 119 consecutive patients treated for renal stones measuring 10-20 mm. According to current recommendations, such patients constitute a border-line group, for which both SWL and endoscopic procedures can be used as the first line treatment.
There were several interesting and important findings in this report. With an overall treatment success (stone-free + CIRF) of 66.4% it is of note that the success-rate for stones in the lower calyx was 70%. Also if only stone-free kidneys were considered, two weeks after SWL treatment, the results were surprisingly similar for stones in different parts of the kidney.
With a complication rate of 11.6 % (6.6 only, if renal colic was excluded as a complication) and a need of auxiliary procedures of 2.5% the overall stone treatment index [1] was 2.52 for stone-free patients and 3.69 for those considered as successfully treated.
The major shortcoming of the method was the relatively high re-treatment rate, but in view of the advantages of SWL the re-treatment rate seems to be a low price to pay.
Reference
1. Tiselius HG, Ringdén I.
Stone treatment index: a mathematical summary of the procedure for removal of stones from the urinary tract.
J Endourol. 2007 Nov;21(11):1261-9.