AUA 2019: Influence of Infundibulopelvic Angle on Success of Retrograde Flexible Ureteroscopy and Laser Lithotripsy for Treatment of Renal Stones

Chicago, IL ( Dr. Stephanie Dresner, a clinical researcher at the University of Wisconsin, presented research evaluating the infundibulopelvic angle and its influence on retrograde flexible ureteroscopy and laser lithotripsy. Conventionally, the lower pole calyces have been difficult to obtain access to than the interpolar or upper pole calyces. The reason that many urologists suspect to be the cause, but has never been studied, is a smaller infundibulopelvic angle in those more difficult patients. To verify this belief, the authors retrospectively measured the stone-free rates of ureteroscopies with laser lithotripsy on patients with a variety of infundibulopelvic angles.

Dr. Dresner and team reviewed 735 renal units of patients who underwent reusable, flexible ureteroscopy before determining 243 units with sufficient pre- and postoperative imaging. They measured standard demographic factors as well as stone free rate, kidney laterality, and preoperative location of the stone. Stone free rate was determined by postoperative ultrasound or KUB within 2 months. They then analyzed the data using univariate analysis.

The team found that ureteroscopy in the lower pole had a significantly lower stone-free rate and a significantly higher residual stone burden. Larger stone size and more acute infundibulopelvic angle were also associated with residual stone burden, leading to needing for an ipsilateral stone procedure within 6 months.

In conclusion, a more acute infundibulopelvic angle of <90˚, larger stone size, and lower pole preoperative stone location are significantly associated with a residual stone burden and repeat stone procedure within 6 months. Dr. Dresner noted that they have not yet compared these characteristics with preoperative imaging to predict outcomes and assist in patient counseling, though they may do that in the future.

Presented by: Stephanie Dresner, MD, Clinical Researcher at the University of Wisconsin, Department of Urology, University of Wisconsin School of Medicine and Public Health

Written by: Vinay Cooper, (Department of Urology, University of California-Irvine) at the American Urological Association's 2019 Annual Meeting (AUA 2019), May 3 – 6, 2019 in Chicago, Illinois
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