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

Ming-Chien Chen,1,2 Ying-Hsu Chang,1,3 Ting-Wen Sheng,1,4 Liang-Kang Huang,1,5 Hung-Chen Kan,1,5 Chung-Yi Liu,1,3 Po-Hung Lin,1,5 Kai-Jie Yu,1,5 Cheng-Keng Chuang,1,5 See-Tong Pang,1,5 Chun-Te Wu,1,5 I-Hung Shao1,5 1Department of Medicine, Chang Gung University, Taoyuan City, Taiwan; 2Department of Urology, Taipei Medical University Hospital, Taipei City, Taiwan; 3Department of Urology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital and Chang Gung University, New Taipei City, Taiwan; 4Department of Medical Imaging and Intervention, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital, New Taipei City, Taiwan; 5Division of Urology, Department of Surgery, Chang Gung Memorial Hospital, Taoyuan City, TaiwanCorrespondence: I-Hung Shao, Email [email protected]: 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.Keywords: robotic-assisted partial nephrectomy, hemorrhagic complication, tumor diameter, tumor depth, nephrometry