Anticoagulation in Pregnancy for DVT/PE

First-line Therapy: Low Molecular Weight Heparin (LMWH)

• Preferred due to:
  • Safety profile (does not cross the placenta).
  • Lower risk of osteoporosis and heparin-induced thrombocytopenia compared to unfractionated heparin (UFH).
• Dosing:
  • Initial Dose: Based on body weight.
    • Enoxaparin: 1 mg/kg subcutaneously every 12 hours or 1.5 mg/kg once daily.
    • Dalteparin: 100 units/kg subcutaneously every 12 hours or 200 units/kg once daily.
  • Adjustment: Monitor anti-Xa levels to ensure therapeutic dosing, especially during the third trimester due to increased renal clearance and blood volume.

Unfractionated Heparin (UFH)

• Used in certain scenarios:
  • High risk of bleeding.
  • Close to delivery due to shorter half-life and reversibility.
• Dosing:
  • Initial Dose: Intravenous (IV) bolus of 80 units/kg followed by an IV infusion of 18 units/kg/hour.
  • Adjustment: Monitor activated partial thromboplastin time (aPTT) to maintain therapeutic levels.

Fondaparinux

• Considered for patients with:
  • Heparin-induced thrombocytopenia.
• Dosing:
  • Prophylaxis: 2.5 mg subcutaneously once daily.
  • Treatment: 5 mg (body weight < 50 kg), 7.5 mg (50-100 kg), or 10 mg (> 100 kg) subcutaneously once daily.
• Note: Limited data in pregnancy, not first-line.

Warfarin

• Contraindicated in pregnancy, particularly during the first trimester (teratogenic) and close to delivery (risk of fetal bleeding).

Monitoring and Adjustment

• LMWH: Periodic monitoring of anti-Xa levels, particularly in the third trimester.
• UFH: Frequent aPTT monitoring.
• Fondaparinux: Monitoring is less established; used in specific cases under specialist guidance.

Peripartum Management

• Switching to UFH: Consider switching from LMWH to UFH close to delivery (around 36 weeks) due to UFH’s shorter half-life and easier reversibility.
• Discontinuation before Delivery: Discontinue LMWH or UFH 24 hours before planned delivery or epidural anesthesia.
• Postpartum Anticoagulation: Restart anticoagulation postpartum with LMWH, transitioning to warfarin if long-term anticoagulation is needed (safe during breastfeeding).

Summary

• LMWH is the first-line treatment for DVT/PE in pregnancy due to its safety and efficacy.
• UFH may be used near delivery or in patients with a high risk of bleeding.
• Fondaparinux can be considered for patients with a history of heparin-induced thrombocytopenia but is not first-line.
• Warfarin is contraindicated during pregnancy due to teratogenic risks.