Treatment of Deep Vein Thrombosis in Pregnancy
For pregnant women with acute DVT, initiate therapeutic-dose low-molecular-weight heparin (LMWH) immediately upon diagnosis and continue throughout pregnancy and for at least 6 weeks postpartum (minimum total duration of 3 months). 1, 2
First-Line Anticoagulation
LMWH is strongly preferred over unfractionated heparin (UFH) for both treatment and prevention of VTE in pregnancy due to superior efficacy, more predictable pharmacokinetics, lower risk of heparin-induced thrombocytopenia, and reduced osteoporosis risk. 1, 2
Dosing Regimens
- Enoxaparin 1 mg/kg subcutaneously twice daily is the preferred regimen for acute DVT treatment 2
- Alternatively, enoxaparin 1.5 mg/kg subcutaneously once daily is acceptable 2
- Either once-daily or twice-daily dosing has similar efficacy 1
Monitoring
- Routine monitoring of anti-factor Xa levels is NOT recommended unless there are specific concerns about achieving therapeutic levels, extremes of body weight, or renal impairment 1, 2
Duration of Therapy
Continue therapeutic-dose LMWH throughout the entire pregnancy and for at least 6 weeks postpartum, with a minimum total treatment duration of 3 months from diagnosis. 1, 2 This extended postpartum period is critical as VTE risk remains elevated up to 12 weeks after delivery. 3
Medications to Absolutely Avoid
- Warfarin and other vitamin K antagonists are contraindicated during the first trimester (embryopathy risk), second and third trimesters, and when delivery is imminent (fetal bleeding risk) 1, 2
- Direct oral anticoagulants (DOACs) including dabigatran, rivaroxaban, and apixaban must be avoided due to placental transfer and lack of safety data 1, 2
- Fondaparinux should be limited to pregnant women with severe heparin allergies (e.g., HIT) who cannot receive danaparoid 1
Outpatient vs. Inpatient Management
Most pregnant women with low-risk acute DVT can be managed as outpatients. 1, 2 However, hospital admission is indicated for:
- Hemodynamic instability 2
- Severe pain or extensive thrombosis 2
- Significant maternal comorbidities 2
- Inadequate home support or inability to self-inject 2
Peripartum Management
Plan for scheduled delivery with discontinuation of therapeutic-dose LMWH 24 hours before anticipated delivery. 1, 2 This timing balances bleeding risk during delivery against thrombosis risk.
- Resume anticoagulation 8-12 hours after vaginal delivery if no significant bleeding 2
- Resume anticoagulation 12-24 hours after cesarean section if hemostasis is adequate 2
Adjunctive Therapy
Prescribe graduated compression stockings starting within 1 month of DVT diagnosis and continuing for at least 1 year to prevent postthrombotic syndrome, which occurs in up to 40% of pregnancy-related DVT cases. 2
Special Circumstances
Iliofemoral DVT with Limb-Threatening Ischemia
- Consider catheter-directed thrombolysis or surgical thrombectomy with or without stent placement 2
- However, catheter-directed thrombolysis is NOT recommended for routine DVT without limb threat 1, 2
Pulmonary Embolism Considerations
- For PE with right ventricular dysfunction but without hemodynamic instability, avoid systemic thrombolysis and use anticoagulation alone 1
- For PE with life-threatening hemodynamic instability, administer systemic thrombolytic therapy in addition to anticoagulation 1
Critical Pitfalls to Avoid
- Do not switch to warfarin during pregnancy even if the patient was on it pre-pregnancy 1
- Do not discontinue anticoagulation early postpartum—the 6-week postpartum period carries the highest VTE risk (≥20-fold increased) 3
- Do not use prophylactic-dose LMWH for acute DVT treatment—therapeutic dosing is required 2
Breastfeeding
UFH, LMWH, warfarin, acenocoumarol, fondaparinux, and danaparoid are all safe during breastfeeding. 1 However, avoid DOACs during breastfeeding. 1