358 VTE timing with routine heparin-based anticoagulation for inpatient obstetric thromboprophylaxis

Abstract

Current guidelines support risk-based obstetric venous thromboembolism (VTE) prophylaxis (ppx), especially in the 1st postpartum (PP) week when VTE risk peaks. At our center, a risk-stratified heparin-based ppx protocol was associated with 2-fold increased PP bleeding/wound morbidity with no change in VTE rate. Here, we examined the protocol’s utility by comparing timing of PP VTE diagnosis in women who did and did not receive inpatient heparin-based VTE ppx. Retrospective cohort study of all deliveries >20 weeks at a single center after adopting a risk-stratified heparin-based VTE ppx protocol (2016-2018). Women anticoagulated for active VTE or high VTE risk were excluded. Women were grouped by documented receipt of inpatient heparin-based ppx (AC) or lack thereof (no-AC). The primary outcome was time from delivery to VTE diagnosis; secondary outcomes evaluated safety and efficacy (Table 2). Outcomes were compared between groups; adjusted odds ratios (95% CI) were calculated with the no-AC group as reference. A sensitivity analysis was performed for cesarean deliveries (CD) only. Of 12,261 total deliveries, 1,915 (16%) were AC. Given the risk-based nature of the protocol, AC and no-AC women were significantly different at baseline (Table 1). AC women had VTE events significantly earlier after delivery, i.e. during PP stay, versus nearly 3 weeks PP in no-AC women (2 days PP [IQR 1-2] vs 20 days PP [IQR 9-32], p=0.005). AC women had more VTEs only in unadjusted analysis; yet, they had significantly more hematomas, overall wound complications, EBL, blood transfusions, and unplanned surgeries even after adjustments (Table 2). Findings limited to CDs were all consistent with primary results. Obstetric VTE ppx aims to prevent PP VTEs, especially early in the PP period when VTE risk is highest; yet, inpatient heparin-based ppx use was associated with VTE events much sooner after delivery, questioning its utility in this population. Given perhaps questionable utility, efficacy, and safety, routine obstetric inpatient heparin-based VTE ppx may need reconsideration.View Large Image Figure ViewerDownload Hi-res image Download (PPT)