CT-based preoperative risk assessment of prolonged urine leak in patients undergoing partial nephrectomy

This study aims to evaluate risk factors of prolonged urine leak following partial nephrectomy (PN) to identify objective imaging characteristics on preoperative CT.

A total of 865 patients who underwent PN and had preoperative CT and postoperative imaging were included. We set a twofold size-matched control group without urine leak, with all tumors located ≤ 4 mm to the collecting system to identify imaging parameters that increase the risk of urine leak other than tumor size and location. Four CT parameters that show the relationship of the tumor and collecting system, namely, curvilinear border length, protruding distance, margin at the interface, and pelvicalyceal contact, were analyzed. Multivariate logistic regression analyses were performed to identify significant predictors of urine leak. The diagnostic performance of the significant parameters was evaluated using the area under the receiver operating characteristic curve (AUC).

Fifty-three of 865 patients (6.1%) demonstrated urine leak. Compared with the control group, urine leak group showed longer curvilinear border length, longer protruding distance, frequent non-smooth contact interface, and frequent direct pelvicalyceal contact (p < 0.05 for all). In the multivariate analysis, pelvicalyceal contact was the independent predictor of urine leak (OR = 2.62; 95% C.I 1.02-6.63). Combining four CT parameters, an AUC of 0.70 with a sensitivity of 58.5% and a specificity of 79.2% for identifying urine leak after PN could be obtained.

The four CT features that describe the relationship between the tumor and collecting system might be useful for evaluating the risk of urine leak before PN.

• Four CT parameters (curvilinear border length, protruding distance, margin at the interface, and pelvicalyceal contact) were significantly associated with postoperative urine leak after partial nephrectomy. • A comprehensive preoperative imaging evaluation of the relationship between the tumor and renal sinus may help in selecting the optimal surgical options and afford better patient counseling of complication risk.