Kim TB et al, 2013: The feasibility of shockwave lithotripsy for treating solitary, lower calyceal stones over 1 cm in size
Kim TB, Lee SC, Kim KH, Jung H, Yoon SJ, Oh JK
Department of Urology, Gachon University Gil Hospital, Incheon, Korea
INTRODUCTION: Recently, few studies were reported about the treatment of large, solitary, renal calculi between shockwave lithotripsy (SWL) and percutaneous nephrolithotomy (PNL). We assess the feasibility of SWL for managing solitary, lower calyceal stones over 1 cm by comparing the results of lower pole calculi treatment between patients that underwent SWL or PNL.
METHODS: We retrospectively reviewed clinical data for patients who had undergone PNL or SWL due to lower calyceal stones over 1 cm. Group 1 consisted of patients who underwent SWL to treat lower pole renal calculi from 2010 to 2011. Group 2 included patients who underwent PNL to manage lower pole renal calculi from 2008 to 2009. We compared patient age, gender, stone size, comorbidities, postoperative complications, additional interventions and anatomical parameters between the two groups.
RESULTS: A total of 55 patients were enrolled in this study. The mean ages (±SD) of groups 1 (n = 33) and 2 (n = 22) were^55.1 (±13.0) and 50.0 (±10.6) years (p = 0.133) and mean stone sizes were 1.6 (±0.7) and 1.9 (±0.8) cm (p = 0.135), respectively. There were no significant differences in gender distribution, comorbidities or stone laterality between the two groups. No significant differences in various parameters were observed between patients with stones 1 to 2 cm and ones with stones 2 cm or larger.
CONCLUSIONS: Our results demonstrated that SWL is a safe, feasible treatment for solitary, lower calyceal stones over 1 cm.
Can Urol Assoc J. 2013 Mar-Apr;7(3-4):E156-60. doi: 10.5489/cuaj.473.
PMID:23589749[PubMed] PMCID:PMC3612404. FREE ARTICLE
The authors compared SWL and PNL for removal of stones larger than 1 cm. Stratification was further made for stones 1-2 cm and > 2 cm. It is of note that all patients were reported stone-free. This result should be compared with the commonly less efficient stone clearance reported in the literature, for instance by Harron et al (Korean Journal of Urology 2013;54:258-262).
The authors use "wide focus, low pressure" shock waves. What that means in terms of shock wave power level is not mentioned. Based on this shortage of information in this regard it is difficult to elucidate the role of treatment parameters for the number of sessions. It is my own impression that for stones in the size range 1-2 cm an average number of 3 sessions seems unusually high, and it is possible that the explanation is a low SW pressure.
Moreover even over-treatment of large stones does not generally result in complete stone clearance. The reason is that anatomical factors play a much greater role than disintegration for the final outcome. The question is if the authors in their analysis only included consecutive stone free patients?