Effect of bladder emptying status on the ureteral access sheath insertion resistance and following ureteral injury in RIRS: a prospective randomized controlled trial in academic hospital.

PURPOSE: To evaluate the effect of bladder emptying status on the ureteral access sheath (UAS) insertion resistance and following ureteral injury. METHODS: Eighty patients were enrolled and randomly divided into bladder emptying group and control group before UAS placement. A digital force gauge (Imada Z2-50N) was used to measure the resistance during the UAS insertion. The ureteral injury was evaluated and graded with Post-Ureteroscopic Lesion Scale (PULS) system at the end of procedure. The mean resistance, maximum resistance in different ureteral segments, and ureteral injury were compared between the two groups. RESULTS: The mean resistance (3.12 ± 0.49 vs. 4.28 ± 0.52 N, P < 0.001), maximum resistance in the whole procedure (5.17 ± 0.72 vs. 6.39 ± 0.96 N, P < 0.001) and distal ureter (3.07 ± 0.75 vs. 6.18 ± 1.17 N, P < 0.001) in the bladder emptying group were significantly lower when compared to the control group. In subgroup analysis, the similar result was also noted in patients with BMI ≥ 25 when compared to patients with BMI < 25, while there was no significant difference between men and women, age ≥ 50 years versus age < 50 years. The incidence of PULS 1-2 ureteral injury in the bladder emptying group was lower than the control group (35% vs. 55%, P = 0.045). The ureteral injury in distal ureteral was less frequently noted in bladder emptying group than the control group (22.5% vs. 55%, P = 0.006); however, there was no significant difference in middle and upper ureter (P > 0.05). CONCLUSION: Emptying the bladder before UAS insertion can effectively reduce the UAS insertion resistance and the risk of distal ureteral injury in RIRS.

Development and internal validation of a prediction model to evaluate the risk of severe hemorrhage following mini-percutaneous nephrolithotomy.

PURPOSE: To develop a new prediction model for assessing the severe hemorrhage events in post mini-percutaneous nephrolithotomy (mini-PCNL) patients and internally validate it, thus to guide decision making in clinical practice. METHODS: The patients who underwent mini-PCNL were retrospectively reviewed. Potential risk factors were included as prediction variables for multivariate logistic regression analysis to identify independent risk factors, and prediction model was constructed. The predictive ability of the model was evaluated using the Concordance index (C-index) and Brier score. Bootstrapping resampling technique was used to perform internal validation. The related packages in R were used to generate the web application based on the prediction model. RESULTS: Multiple-tract was the strongest predictor of severe hemorrhage following mini-PCNL. Other risk factors were none or mild hydronephrosis, congenital anomalies of urinary system, urinary tract infection, operation time and stone peak Hounsfield unit. A prediction model was constructed to assess the probability of severe hemorrhage after mini-PCNL. The C-index and Brier score were 0.731 and 0.093, respectively after correcting for optimism, which signified the excellent discrimination and calibration. CONCLUSION: A new prediction model was developed to estimate risk of severe hemorrhage after mini-PCNL. It had been internally validated with good discrimination and calibration. The prediction model might be beneficial for endourologists in surgical decision-making and risk aversion.