Removal of Asymptomatic Kidney Stones Reduces Risk of Relapse

Symptomatic stones in the kidney or ureters are frequently removed endoscopically. During these procedures, smaller asymptomatic stones are often noted on imaging. Guidelines are unclear about whether to remove or observe these stones and “leave such decisions to the urologist and the patient,” wrote Mathew Sorensen, MD, MS, FACS, and colleagues in NEJM. A prospective study involving shockwave lithotripsy, as well as previous retrospective studies, support observation. Nevertheless, approximately 50% of these small stones become symptomatic within 5 years of initial surgery.

The present study was a multicenter, randomized, controlled trial in which patients undergoing endoscopic removal of stones in the ureter or contralateral kidneys had their small, asymptomatic stones removed (treatment group) or observed (control group). The treatment group was found to have a longer time to relapse and a lower incidence of relapse within an average follow-up of
4.2 years. The two groups had no difference in emergency visits relating to the surgery.

Despite its small sample size and lack of sub analysis of surgical technique variability, this study provided the first prospective evidence of the potential benefits of pre-emptive removal of asymptomatic stones in reducing relapse risk.

In-Depth [Randomized Controlled Trial]

This randomized controlled trial assessed outcomes associated with concurrent pre-emptive removal of small, asymptomatic renal stones during endoscopic surgery for symptomatic stones. Patients were screened for inclusion if they were aged 21 or older, scheduled for endoscopic treatment of a primary stone, and had small secondary stones (<6mm) detected via computed tomography (CT). In total, 75 patients were randomized 1:1 to have the secondary stones removed by ureteroscopy (treatment group) or observed (control group). The primary outcome was relapse, defined as: 1) an emergency department visit due to stones originating from the kidney with secondary stones (trial side); 2) surgery to remove stones on the trial side; or 3) growth of the original secondary stones.

After an average follow-up of 4.2 years, the treatment group had a significantly longer time to relapse (1631.6±72.8 days [mean ± standard error]) compared with the control group (934.2±121.8 days; P<0.001). The risk of relapse was 82% lower in the treatment group (HR, 0.18; 95% CI, 0.07-0.44). The pre-emptive removal of secondary stones added a median of 25.6 minutes
to the operation. Emergency department visits within 2 weeks of the surgery occurred in 13% of the treatment group and 11% of the control group (OR, 1.17; 95% CI, 0.29-4.78). New stone growth was detected via imaging in the same proportion (37%) of the treatment group and the control group (OR, 0.99; 95% CI, 0.38-2.56). “Eight patients in the treatment group and 10 in
the control group reported passing kidney stones,” wrote Dr. Sorensen and colleagues.

In summary, this trial provided the first evidence to support the pre-emptive removal of asymptomatic stones during endoscopic removal of primary stones. “The removal of small, asymptomatic kidney stones during surgery to remove ureteral or
contralateral kidney stones resulted in a lower incidence of relapse than non-removal and in a similar number of emergency department visits related to the surgery,” Dr. Sorensen and team added.

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