Contralateral Coupling During Extracorporeal Shockwave Lithotripsy for Stones in Ectopic Kidney: Is It Feasible?

Extracorporeal shockwave 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. 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 postprocedural SWL variables were assessed, including stone characteristics, body habitus, shock wave numbers, and auxiliary measures. Count and percentages were calculated. The mean stone radius was 14.7 mm with a mean S.T.O.N.E. (size, topography, obstructions, number of stones, and evaluation of HUs) of 9.6 points. Effective SWL was achieved in 80% of cases, 65% of them were stone free with effective 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. 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.