AUA 2019: Effectiveness of Ultrasound versus Intraoperative Residual Stone Burden Evaluation

Chicago, IL ( Ureteroscopy with laser lithotripsy is the most commonly employed surgical modality for the management of urolithiasis. Residual stone fragments that are left behind postoperatively predispose to unplanned hospital visits for stone-related symptoms and recurrence of stone disease. In an effort to address how surgeons can most effectively identify residual fragments, Dr. Kott and colleagues sought to compare the effectiveness of ultrasound (US) versus intraoperative residual stone burden evaluation (IRSBE) in predicting adverse clinical outcomes. The authors described IRSBE as simply the surgeon’s inspecting the surgical field for any residual stones >3mm prior to completion of the procedure. 

The study included 263 patients who were followed for 3 months. Notably, US exhibited a higher sensitivity in detecting residual fragments compared to IRSBE. However, when residual stones >3mm were identified on IRSBE, there was a significantly higher (p=0.03) likelihood that the patient would have an unplanned encounter in the postoperative period (Table 1). In contrast, residual fragments seen on US was not a significant predictor, indicating a high false positive rate for US. Presence of residual stones >3mm on both IRSBE and US was the best predictor an unplanned encounter (p=0.008). 

A robust discussion regarding the role of post-ureteroscopy US followed the presentation. Dr. Kott was asked if he believes US has any place in postoperative residual stone assessment. He responded that, based on his findings of a high false positive rate for US, clinicians should consider US only if IRSBE is inconclusive. Alternatively, if the surgeon feels confident that no fragments >3mm were left behind during surgery, then US is likely not worthwhile. 

An audience member also pointed out that longer follow-up of 6 months and 1 year would be of interest, given that 3 months is not necessarily a sufficient end point to fully characterize sequelae of residual fragments. 

Table 1.Multivariate analysis of the effectiveness of intraoperative residual stone burden evaluation (IRSBE) vs. postoperative ultrasound (US) in predicting unplanned encounters after ureteroscopy with laser lithotripsy. 

Presented by Ohad Kott, MD, The Miriam Hospital; Warren Alpert Medical School of Brown University, Providence, RI

Co-authors: Alison Chambers, Osama Al-Alao, Eric Jung, Timothy O’Rourke, Meredith Wasserman, Alejandra Balen, Mina Ghaly, Timothy Wright, Stefan Rodriguez, Siddharth Marthi, Christopher Tucci, Gyan Pareek 

Written by Frank Jefferson, 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