Outcomes of primary ureteroscopic lithotripsy: The role of maximum ureteral wall thickness at the site of stone impaction.

Objectives: To verify if the maximum thickness of the ureteral wall at the stone site (m-UWT) can affect the outcomes of primary retrograde ureteroscopic lithotripsy (P-URSL) within a single-center dataset.

Material And Methods: We retrospectively reviewed data on 354 consecutive URSL performed from January 2020 to May 2022 at "Fondazione Poliambulanza" in Brescia (Italy). We included patients older than 18 years who underwent URSL for a single ureteral stone with a maximum diameter ranging from 5 to 10 mm. Patients with anatomical abnormalities, a positive preoperative urinary culture, or without a NCCT performed during the acute event were excluded. Patients were treated in an emergency setting (P-URSL within 48 h from the diagnosis of acute ureteral colic) or in a delayed one (D-URSL after a period of maximum 90 days of ureteral double-j stenting). For the resulting 139 patients we recorded demographic, clinical and stone-related features and perioperative data. We processed these data by univariate and multivariate analysis, and with a logistic regression analysis.

Results: Of the 139 included procedures, 63 were P-URSL and 76 D-URSL. At the univariate analysis we found that stone diameter (OR 0.845,  = 0.017), stone volume (OR 0.023,  = 0.001), stone density (OR 0.998,  = 0.000) and m-UWT (OR 0.499,  = 0.013) are predictors of P-URSL. Stone density (OR 0.998,  = 0.002) is an independent predictor of P-URSL at the multivariate analysis. At a logistic regression analysis, a distal ureteric position (OR 0.189,  = 0.014), stone diameter (OR 1.289,  = 0.006), and m-UWT (OR 2.297,  = 0.02) were found to be statistically significant predictors of incomplete stone clearance in patients undergoing P-URSL. m-UWT is the only predictor of short-term postoperative adverse events in patients undergoing P-URSL (OR 3.386,  < 0.001). From a descriptive analysis, it emerged that an increased m-UWT (>2 mm) significantly correlates to an endoscopic finding of ureteritis' signs and to an increase in operative time, hospital stay and post-procedural stenting time. A m-UWT greater than 2 mm also correlates with a lower stone free rate (SFR) and with a significant increase in both short and long-term postoperative complications.

Conclusions: Our study confirmed a connection between m-UWT and poor endoscopic findings, as well as a direct correlation with the main morphometric parameters of the stone and finally with the outcomes of P-URSL itself. Further studies are necessary to validate our results, so that m-UWT might be routinely considered a useful tool in the decision-making process for P-URSL.