A 35-year-old woman undergoes evaluation after home pregnancy testing indicated that she is pregnant. Her medical history includes a previous idiopathic pulmonary embolism. Her only medication is a daily prenatal vitamin.
On physical examination, temperature is 36.2 °C (97.1 °F), blood pressure is 110/65 mm Hg, pulse rate is 70/min, and respiration rate is 20/min. BMI is 25.
Results of a pregnancy test are positive.
Which of the following is the most appropriate venous thromboembolism prophylaxis for this patient?
A: Antepartum low-molecular-weight heparin (LMWH) and aspirin
B: Antepartum and postpartum LMWH
C: Antepartum and postpartum warfarin
D: No prophylaxis
MKSAP Answer and Critique
The correct answer is B: Antepartum and postpartum LMWH. This item is available to MKSAP 16 subscribers as item 43 in the Hematology and Oncology section.
This patient should receive antepartum and postpartum heparin. Patients such as this one with a previous history of idiopathic venous thromboembolism (VTE) are at a fourfold increased risk for recurrent VTE compared with patients with a history of triggered VTE. Although outcomes data are limited, it is currently recommended that pregnant women at moderate to high risk of recurrent VTE (as in this patient with a single unprovoked pulmonary embolism) receive prophylactic-dose or intermediate-dose low-molecular-weight heparin (LMWH) during pregnancy and for 6 weeks postpartum.
Prophylaxis with both low-dose aspirin and low- or moderate-dose unfractionated heparin or LMWH is indicated for women with recurrent fetal loss and the antiphospholipid syndrome. This patient does not have the antiphospholipid syndrome or previous fetal loss, and combined aspirin and heparin treatment is not indicated.
Warfarin is contraindicated during the first trimester because of the potential for warfarin-induced embryopathy. In addition, warfarin is rarely used in the United States during the second and third trimesters, generally because of the fear of liability in the event of any fetal adverse events, whether or not they are warfarin related.
Administering no prophylaxis to this patient with a high risk for recurrent VTE would not be prudent.
- Pregnant women with a history of idiopathic venous thromboembolism should receive antepartum and postpartum prophylactic anticoagulation.
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