Predicting Bleeding Related Events in Robotic-Assisted Partial Nephrectomy for Angiomyolipoma: Simplifying Risk Assessment with Tumor Diameter and Depth, A Retrospective Study.

Background: Evaluating risk factors for bleeding events in robot-assisted partial nephrectomy (RAPN) for renal angiomyolipoma (RAML) is essential for improving surgical outcomes.

Methods: We performed a retrospective analysis of patients who underwent RAPN for renal masses between May 2019 and June 2023 at a single medical center, categorizing them into AML and non-AML groups. We assessed demographic data, perioperative complications, and postoperative outcomes. Preoperative imaging was reviewed to calculate R.E.N.A.L and PADUA nephrometry scores. Receiver operating characteristic (ROC) curve analysis was used to evaluate the accuracy of risk factors related to estimated blood loss (EBL) and blood transfusion.

Results: Among 255 patients, 71 (27.8%) had AML, and 184 (72.2%) had non-AML. The average age was 54.5 years, with 80.2% of the AML group being female. The median tumor size was 50.2 mm. The AML group had larger tumor diameters (50.2 mm vs 34.9 mm) but shallower depths (16.1 mm vs 21.7 mm). Median R.E.N.A.L and PADUA scores were 6.5 and 8.2, respectively, with a median EBL of 128.2 mL. Blood transfusion was required in 15.5% of cases. Tumor diameter, depth, R.E.N.A.L score, and PADUA score significantly correlated with EBL, while BMI, tumor diameter, and R.E.N.A.L score correlated with blood transfusion. The AUCs for predicting EBL and blood transfusion were 0.778 and 0.771 for tumor diameter, and 0.661 and 0.711 for R.E.N.A.L score.

Conclusion: RAPN might be a safe option for RAML, with tumor diameter being the most accurate predictor of EBL and blood transfusion. These findings can improve preoperative assessments and surgical planning.