Preemptive anticoagulation during antenatal pulmonary embolism diagnostics in a community setting: retrospective cohort study.

Background: Society recommendations for preemptive (or empiric) anticoagulation during antenatal pulmonary embolism (PE) diagnostics rely on expert opinion, which varies widely across guidelines. The American College of Chest Physicians (CHEST), for example, recommends preemptive anticoagulation when PE is highly suspected or when a delay in imaging is anticipated. The American College of Obstetricians and Gynecologists, however, makes no mention of preemptive anticoagulation for suspected PE in their practice bulletin on thromboembolism in pregnancy. Patterns of preemptive anticoagulation in pregnancy are unknown.

Objectives: To describe the prevalence of and CHEST-based eligibility for preemptive anticoagulation in pregnancy.

Methods: This retrospective cohort study was undertaken across 21 United States community hospitals from October 1, 2021 through March 30, 2023. We included pregnant adults without COVID-19 undergoing definitive diagnostic PE imaging. We used pregnancy-adapted Geneva scores to calculate pretest probability as a proxy for suspicion.

Results: We included 326 patients: median age, 31.0 years; 51% were in the third trimester. Diagnostic settings included emergency departments ( = 254; 78%), Labor & Delivery ( = 65; 20%), and outpatient clinics ( = 7; 2%). Median time from emergency department computed tomography order to results was 1.40 hours (IQR: 0.78, 2.06). Prevalence of confirmed or presumed PE was low ( = 8; 2.5%). Only 2 patients (0.6%) received preemptive anticoagulation, whereas by CHEST criteria, 34 patients (10.4%) were eligible.

Conclusion: We found rare use of preemptive anticoagulation during antenatal PE diagnostics in this imaged cohort with low PE prevalence and rapid access to diagnostic imaging. More research is needed to explore setting-specific variation in preemptive anticoagulation use.