Fawzy AM. et al., 2021: Contralateral Coupling during SWL for Stones in Ectopic Kidney: Is It Feasible?
Iremashvili V, Li S, Dresner SL, Best SL, Hedican SP, Nakada SY.
Faculty of Medicine, Minia Urology and Nephrology University Hospital, Minia University, Minia, Egypt.
Nile SWL Center, Minia, Egypt.
Department of Urology, School of Medicine, Minia University, Minia, Egypt.
Purpose: Shock wave lithotripsy (SWL) results in a lower stone-free rate (SFR) for ectopic kidneys when using the standard technique, directing the shock wave from the same side of the stone; however, this may not be the optimal approach when the ectopic kidney is located more medial and anterior than the normally-positioned kidney. Thus, contralateral coupling where waves come from the opposite direction may result in a better outcome. We tested the feasibility and outcome of contralateral coupling during SWL for stone in ectopic kidney.
Material and methods: We prospectively recruited 20 patients with simple renal ectopia, who presented with renal stones that were amenable for SWL in the period between 2014 and 2018 at outpatient clinic of Urology Department, Minia University. Patients received SWL in Private Nile SWL Center were included to benefit from the ability of the electromagnetic SWL lithotripter. We did SWL in a supine position, and then contralateral coupling was performed from the opposite side of the affected kidney, rather than using the standard ipsilateral coupling approach. The SFR and various pre-, intra-, and post-procedural SWL variables were assessed, including stone characteristics, body habitus, shock wave numbers, and auxiliary measures. Count and percentages were calculated.
Results: The mean stone radius was 14.7 mm with a mean S.T.O.N.E of 9.6 points. Successful SWL was achieved in 80% of cases, 65% of them were stone free with successful single SWL session in 56% of cases. Hematuria, infection and obstruction occurred in 50%, 20% and 15% cases respectively. One case required ureteral stent insertion.
Conclusions: SWL applied through contralateral coupling is feasible, with comparable safety profile to the standard ipsilateral approach. Better SFR was achieved with the contralateral approach, in fewer sessions. However, the recruitment of more cases is necessary.
J Endourol. 2021 Feb 5. doi: 10.1089/end.2020.1064. Online ahead of print. PMID: 33544033.
It is well recognized that treatment of stones in ectopic kidneys is a demanding task. This report clearly emphasizes the need and value of individualized patient positioning during SWL. Although the standard procedure used by most urologists for most stones is to direct shockwaves from the back with the patients in supine position, this approach is often not possible for ectopic kidneys such as horseshoe kidneys and pelvic kidneys. Skeletal structures, surrounding organs and long distance between the sw-source and the stone(s) are problems that will be encountered.
In this report based on 20 patients treated with SWL for stones in ectopic kidneys, the authors found that contralateral coupling was successful. All treatments were carried out with the Dornier Medipuls lithotripter.
The argument for choosing this alternative shockwave direction was the observation that ectopic kidneys were located “more anteriorly and medially than normal kidneys”. With the lithotripter that the authors used is it possible to rotate the shockwave cushion and thus facilitate anterior coupling. With this approach the authors were successful and achieved a stone-free rate of 81% with CIRF in 19%. Interestingly as many as 56% of the patients were treated with only one session and the overall number of sessions was 34, which gives an average of 1.7 treatment sessions per kidney.
One of the problems encountered when directing shockwaves transabdominally is the presence of intestinal gas. To deal with that problem the authors administered two tablets of activated charcoal every 4 hours and 7.5 mg of sodium picosulfate.
The limiting factor was that patients were given 3500 shockwaves at “the maximum tolerable power”. It is not known exactly what this means, but it had probably been even better if analgesics had been given in a dose allowing the power necessary to break the stone without being restricted by the patient´s reaction.