Evaluation of a Risk-Stratified, Heparin-Based, Obstetric Thromboprophylaxis Protocol

Abstract

OBJECTIVE: To evaluate outcomes before and after implementation of a risk-stratified heparin-based obstetric thromboprophylaxis protocol. METHODS: We performed a retrospective cohort study of all patients who delivered at our tertiary care center from 2013 to 2018. Deliveries were categorized as preprotocol (2013–2015; no standardized heparin-based thromboprophylaxis) and postprotocol (2016–2018). Patients receiving outpatient anticoagulation for active venous thromboembolism (VTE) or high VTE risk were excluded. Coprimary effectiveness and safety outcomes were postpartum VTEs and wound hematomas, respectively, newly diagnosed after delivery and up to 6 weeks postpartum. Secondary outcomes were other wound or bleeding complications, including unplanned surgical procedures (eg, hysterectomies, wound explorations) and blood transfusions. Outcomes were compared between groups, and adjusted odds ratios (aORs) and 95% CIs were calculated using the preprotocol group as reference. RESULTS: Of 24,229 deliveries, 11,799 (49%) occurred preprotocol. Although patients were more likely to receive heparin-based prophylaxis postprotocol (15.6% vs 1.2%, P<.001), there was no difference in VTE frequency between groups (0.1% vs 0.1%, odds ratio 1.0, 95% CI 0.5–2.1). However, patients postprotocol experienced significantly more wound hematomas (0.7% vs 0.4%, aOR 2.34, 95% CI 1.54–3.57), unplanned surgical procedures (aOR 1.29, 95% CI 1.06–1.57), and blood transfusions (aOR 1.34, 95% CI 1.16–1.55). CONCLUSION: Risk-stratified heparin-based thromboprophylaxis in a general obstetric population was associated with increased wound and bleeding complications without a complementary decrease in postpartum VTE. Guidelines recommending this strategy should be reconsidered.

Adjunctive Azithromycin Prophylaxis for Prelabor Cesarean Birth

“…The strengths of our study include a large cohort size of 2,867 patients, with detailed chart review for all patients using methods that have been published previously. 16 Our population was diverse in terms of race and ethnicity, payer status, and marital status, making our results generalizable to other populations across the country. The study was performed at a single institution, with consistent surgical practices and no variation in surgical technique, general intraoperative management, or postpartum care over the study time period.…”

“…This study timeline was specifically chosen because we used a previously assembled obstetric database from these dates. 16 Our institution is a large academic tertiary care referral center, with more than 4,000 deliveries annually. IRB approval was obtained before study initiation (IRB-300002492).…”

Evaluation of a Risk-Stratified, Heparin-Based, Obstetric Thromboprophylaxis Protocol

“…Friedman and D'Alton for their interest in our work in the October 2021 issue evaluating a riskstratified, heparin-based obstetric thromboprophylaxis protocol. 1 Our study examining bleeding and other perinatal outcomes in a significantly larger population with both vaginal and cesarean deliveries after implementation of a strict risk-based thromboprophylaxis protocol greatly enhances estimates published in smaller studies. 2 The authors pose questions related to our power calculations.…”

Risk assessment models for venous thromboembolism in pregnancy and in the puerperium: a systematic review

“…Despite the limitations of undertaking accuracy studies in populations where thromboprophylaxis is routinely used, future research could focus on selected higher risk groups who are more likely to benefit from prophylaxis and, with a higher prevalence of VTE, are more amenable to an appropriately powered prospective study. However, given the uncertain benefits and harms of VTE thromboprophylaxis during pregnancy and the postpartum period,14 48 risk prediction studies should be undertaken alongside (or as a part of) randomised trials of prophylaxis in targeted groups deemed to be at higher risk of VTE.…”