Removing small, asymptomatic kidney stones during endoscopic surgery may reduce the risk for relapse, according to new study findings published in the New England Journal of Medicine.

In a multicenter trial, 73 patients who were undergoing surgery for a primary large or obstructive stone in the ureter or kidney also had secondary 6 mm or smaller asymptomatic stones (90% in the contralateral kidney). Investigators randomly assigned 38 patients to removal and 35 patients to no removal of the small stones via ureteroscopy following surgery for the primary stone. Removal of small stones added a median 25.6 minutes to the operating time.

Removal of small stones significantly reduced the risk of relapse by 82%, with 16% of the treatment group vs 63% of the control group experiencing relapse, corresponding author Michael R. Bailey, PhD, of the University of Washington in Seattle and colleagues reported. Relapse included emergency department visits for stones, additional surgery, or growth of secondary stones in the ipsilateral kidney within 5 years.

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The treatment group had a significantly longer time to relapse compared with the control group. The restricted mean time to relapse was 75% longer among treated than untreated patients: 1631.6 vs 934.2 days, the investigators reported.

According to the investigators, the trial findings demonstrate the efficacy and safety of treating ureteral and kidney stones in a single setting, combining ureteroscopy and percutaneous nephrolithotomy, and performing bilateral endoscopic procedures.

“Results of our prospective, randomized trial support removal of small, asymptomatic renal stones at the time of surgery to remove a symptomatic stone,” Dr Bailey’s team wrote.

In the treatment group, 7 of the 38 patients had residual fragments after ureteroscopy. A comparable proportion of the treatment and control groups sought emergent care within 2 weeks of surgery (13% vs 11%), experienced kidney stone passage (21% vs 29%), and had new stone formation (37% in both groups). Approximately a quarter of patients were taking preventive medications.

In an accompanying editorial, David S. Goldfarb, MD, of New York Harbor Veterans Affairs Healthcare System and the Division of Nephrology at NYU Grossman School of Medicine in New York, New York, lauded the trial, writing, “Although the results are not surprising, the trial was worth conducting.”

Dr Goldfarb also observed: “Patients who have had symptomatic stones often recall harrowing emergency department visits and dread a lack of appropriate analgesia. They worry about the threat posed by those ‘trivial,’ ‘benign’ calcifications seen on imaging studies. One can imagine that elective removal may allow these patients to avoid pain and trauma, inefficient and costly emergency department visits, infections, receipt of pain medications, and additional imaging studies.”

He noted that several key questions still need to be answered. Most importantly, when should small asymptomatic stones be removed surgically and which specialists should perform it?

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original references for a full list of authors’ disclosures.


Sorensen MD, Harper JD, Borofsky MS, et al. Removal of small, asymptomatic kidney stones and incidence of relapse. N Engl J Med 387:506-513. Published online August 10, 2022. doi:10.1056/NEJMoa2204253

Goldfarb DS. Preemptive removal of small, asymptomatic kidney stones. N Engl J Med 387:562-563. Published online August 10, 2022. doi:10.1056/NEJMe2208287