Development and internal validation of a nomogram to predict perioperative complications after flexible ureteroscopy for renal stones in overnight ureteral catheterization cases

Purpose To identify risk factors by developing and internally validating a nomogram for preventing perioperative complications in overnight ureteral catheterization cases after fURS for kidney stones. Methods We retrospectively examined 309 patients with overnight ureteral catheterization after single fURS procedures for renal stones. fURS procedures were performed based on the fragmentation technique. The ureteral catheter was removed on postoperative day 1. Within this group, patients who experienced perioperative complications (complication group) were compared with those who did not experience complications (non-complication group). The complication group included 77 patients whose Clavien-Dindo classification score was I, II, III, or IV and/or those whose body temperature during hospitalization was over 37.5 degrees C. Results The overall stone volume, stone-free rate, incidence of perioperative complications, and procedure duration were 1.39 mL, 94.8%, 24.9%, and 62 min, respectively. Severe complications of a Clavien-Dindo level III or IV were observed in only four cases (1.3%). Multivariate assessment revealed five independent predictors of perioperative complications after fURS with overnight catheterization: age (p = 0.11), sex (p = 0.067), stone volume (p = 0.33), Hounsfield units (p = 0.16), and narrow ureter (p = 0.018). We developed a nomogram to predict perioperative complications after fURS using these parameters. Conclusions We developed a predictive model for perioperative complications of patients with overnight catheterization after fURS for renal stones. This model could select patients who were at a low risk of complications.