Endoscopic Evaluation of Ureteral Stone Impaction Highlights Significant Variability in Definitions Between Endourologists

Introduction: Previous studies attempting to predict impaction on CT have relied on various criteria without a gold standard for comparison. Intraoperative single-surgeon estimations of impaction have been unvalidated and subjective. This study aimed to investigate surgeon perspectives and variability in estimating ureteral stone impaction based on a curated ureteroscopy video catalog. Methods: A catalog of 35 primary ureteroscopy cases was distributed to a group of fellowship-trained endourologists. All videos featured visual inspection of tissue around the stone, attempted passage of a guidewire adjacent to the stone, and an attempt to dislodge the stone with gentle nudging of the scope. Participants independently rated impaction on two different scales: continuous (0–9) and categorical (none/mild/moderate/severe). After a first pass, participants rated the videos in a new, random order. Inter- and intrarater agreement across both rating systems was evaluated. Results: In total, 35 videos were evaluated by 13 endourologists. Overall, 13/35 videos had strong agreement (>70%) on the degree of impaction (6 none, 7 severe), and only 2 of these had 100% agreement (1 none, 1 severe). Continuous scale ratings mirrored the categorical ratings for the none and severe impaction cases. There were no cases with consensus agreement of mild or moderate impaction. More than one-third (12/35) of videos had at least one vote for each of the four severity categories, indicating stark disagreement between surgeons on what constitutes impaction. Conclusions: There is significant variability among endourologists regarding the definition and severity of stone impaction. When strong agreement occurs, it is when a stone is deemed to be severely impacted or not impacted. Further work is needed to create a standardized definition of impaction based on objective endoscopic criteria. A tripartite classification system may be the most appropriate manner of grouping ureteral stones based on impaction.