Management of Pregnant Woman with History of DVT
A 40-year-old healthy primigravida with a history of previous deep venous thrombosis should receive therapeutic anticoagulation with low-molecular-weight heparin (enoxaparin) throughout pregnancy and for at least 6 weeks postpartum, with a minimum total duration of 3 months. The correct answer is C. Enoxaparin.
Rationale for LMWH (Enoxaparin)
Low-molecular-weight heparin is the first-line therapy for VTE treatment in pregnancy because it does not cross the placenta and provides superior efficacy and safety compared to other anticoagulants. 1, 2, 3
- LMWH is strongly preferred over unfractionated heparin for both prevention and treatment of VTE in pregnancy, offering superior bioavailability, more predictable anticoagulant response, and reduced risk of heparin-induced thrombocytopenia 2, 3
- The American College of Chest Physicians recommends LMWH as first-line therapy throughout pregnancy with continuation for at least 6 weeks postpartum (Grade 1B evidence) 2
- Neither LMWH nor unfractionated heparin crosses the placenta, making them safe for the fetus 3, 4
Why Other Options Are Incorrect
Aspirin (Option A) is inadequate because it provides insufficient anticoagulation for a patient with prior DVT who is at 5-times higher risk of VTE during pregnancy. 1
Unfractionated heparin (Option B) is inferior to LMWH due to less predictable pharmacokinetics, need for monitoring, and higher risk of complications including heparin-induced thrombocytopenia. 2, 3
No anticoagulation (Option D) is dangerous given that pregnancy increases VTE risk 5-fold, with absolute risk of 0.5-3.0 per 1000 women, and this patient has a prior DVT history placing her at even higher risk. 1
Treatment Protocol
- Dosing: Either once-daily or twice-daily LMWH dosing regimens can be used (typically 1 mg/kg subcutaneously twice daily for enoxaparin) 3, 5
- Duration: Continue therapeutic anticoagulation throughout pregnancy and for at least 6 weeks postpartum, with minimum total duration of 3 months from diagnosis 2, 3
- Monitoring: Routine monitoring of anti-factor Xa levels is not recommended unless there are specific concerns about therapeutic levels 3
Peripartum Management
- Schedule delivery with planned discontinuation of LMWH at least 24 hours before anticipated delivery or neuraxial anesthesia 3, 4
- After delivery, either continue LMWH or transition to warfarin, as both are safe during breastfeeding 2, 4
Critical Contraindications
Warfarin must be avoided entirely during the first trimester due to teratogenicity (embryopathy between 6-12 weeks' gestation) and fetal bleeding risks at delivery. 2, 3
Direct oral anticoagulants (DOACs) are absolutely contraindicated in pregnancy due to lack of safety data and potential fetal harm. 2, 6