A ureteral stricture disease (USD) score and classification system: correlation with upper urinary tract reconstructive surgery complexity

Background: To develop an original and standardized ureteral stricture disease (USD) score and classification system for quantifying ureter stricture characteristics, assessing complexity of the minimally invasive upper urinary tract reconstructive (UUTR) surgical procedure, formulating preoperative plans, and offering objective comparisons of surgical techniques between different institutions and surgeons. Methods: We retrospectively reviewed a test set of 64 patients and a validation set of 170 patients who underwent minimally invasive UUTR surgery from January 2018 to January 2021. Three factors were selected to be included in the USD score and classification system: (I) stricture etiology (E, 1-2 points); (II) stricture segment (S, 0-3 points); and (III) length of stricture (L, 1-5 points). The UUTR surgery involves low-complex surgeries (cystoscopy with ureteral dilation and stent placement, ureteropyeloplasty, end to end repair, ureteral reimplantation) and high-complex surgeries (onlay repair (buccal mucosae, lingual mucosae, appendix mucosae), Boari flap repair and ileal ureter replacement). Estimated blood loss and operative time were used as surrogate indicators of surgical complexity. Results: The interrater reliability of the USD score and classification system was 0.908. A linear relationship between the USD score and estimated blood loss was observed (rs=0.676, P<0.001). The USD score was also correlated with operative time (rs=0.638, P<0.001). A significant difference in USD scores was found between the high and low complexity surgery groups (4 vs. 7, P<0.001). Variability of UUTR surgery is based on USD classification system, but with regularity to conform to. Conclusions: The USD score and classification system is a concise, easily applicable, and validated scale to delineate the clinically significant features of ureter stricture that correlate with the complexity of the UUTR surgical procedure. The use of this score and classification system can facilitate preoperative plan and comparison of USD treatments in clinical practice and urological literature. Research with large sample is needed to further examine and modify the use of the system.