(614) Predicting Severe Blood Loss Before Cesarean Hysterectomy (CH): A Novel Method Focusing on Bladder Vascularity

Objective: Placenta accreta spectrum (PAS) grade 3b&c pose the highest risk for severe blood loss (SBL) during CH, primarily due to bladder dissection. Interventions like interval hysterectomy, conservative management and aortic occlusion (REBOA) are proposed to reduce SBL but come with complications. Current preoperative assessments are unreliable in identifying SBL cases. We hypothesize that cystoscopic (C) evaluation can accurately predict SBL.

Study Design: PAS cases had preoperative ultrasound, MRI, and postoperative pathological grading. Standardized cystoscopy and bilateral stents were used in non-urgent cases. Quantitative blood loss (QBL), surgical complications, and transfusions were recorded. Same surgeon, standardized techniques, and blinded evaluation of C recordings were inclusion criteria (Figure 1). Odds ratio (OR) for cystoscopy variables were calculated using postoperative grading. The Cystoscopy Index (CI) was calculated from OR sums. Postoperative grades 3b&c were high grade (HG); 1, 2, and 3a were low grade (LG). Primary outcome was CI prediction of SBL > 2000ml. Secondary outcomes included surgical complications and REBOA placement. C results were analyzed using descriptive statistics, correlation, and ROC curve.

Results: Of 66 cases, 31 were HG and 35 LG. Postoperative grading identified more HG cases than preoperative (p=0.002), with grade 3b being the most common (38%). Bridging vessels (BV) and distortion of the trigone (DT) were the strongest predictors of HG (odds ratios 3.5 and 5.1, p=0.01). CI correlated with QBL (p=0.036). ROC analysis calculated CI ≥ 2.8 is the predictor for HG cases (AUC:0.68, p=0.009). CI ≥ 2.8 was identified in 82% (14/17) of cases with SBL and required >4U RBC transfusion (p=0.01 and 0.03) (Table 1). DT was significantly related to cystotomy (p=0.007). Two HG cases required REBOA and had CI ≥ 2.8.

Conclusion: Preoperative cystoscopy and CI can identify cases resulting in SBL, unavoidable cystotomy, and REBOA. High CI can guide discussions about alternatives like interval hysterectomy or REBOA. This tool aids in randomizing patients for conservative management.