MKSAP: 32-year-old woman is evaluated for anticoagulation management

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 32-year-old woman is evaluated for anticoagulation management after an uncomplicated vaginal delivery of a healthy newborn. She was diagnosed with a bilateral pulmonary embolism at 25 weeks’ gestation and was treated with therapeutic low-molecular-weight heparin (LMWH). The LMWH was discontinued at the onset of labor and was restarted 6 hours after delivery. Medical history is otherwise unremarkable, and her only medication is full-dose LMWH.

Anticoagulation for 3 months is planned. The patient wishes to breastfeed her newborn.

Which of the following is the most appropriate anticoagulation option for this patient?

A: Apixaban
B: Dabigatran
C: Fondaparinux
D: Rivaroxaban
E: Warfarin

MKSAP Answer and Critique

The correct answer is E: Warfarin.

Warfarin would be the most appropriate anticoagulation option for this patient. Warfarin is avoided during pregnancy because it crosses the placenta, causes fetal anticoagulation throughout the pregnancy, and is a teratogen. Because heparins do not cross the placenta and do not cause fetal anticoagulation, patients receiving chronic warfarin therapy are typically transitioned to either unfractionated or low-molecular-weight heparin (LMWH) during pregnancy. However, warfarin is not present in breast milk in any substantial amount and does not induce an anticoagulant effect in the breastfed infant. It is, therefore, a good option for anticoagulation in this patient. Similarly, heparins are minimally excreted in breast milk, and any drug ingested by an infant is unlikely to have any clinically relevant effect because of the very low bioavailability of oral heparins. Thus, LMWH and warfarin are both appropriate anticoagulant options for women who want to breastfeed.

It is unknown whether apixaban, dabigatran, or rivaroxaban are excreted in human milk. Therefore, known safe alternatives to these new oral anticoagulants should be used in women intending to breastfeed.

Fondaparinux has been demonstrated to be excreted in the milk of lactating rats. It is unknown whether it is excreted in human milk. Therefore, an alternative anticoagulant rather than fondaparinux is recommended for women who breastfeed.

Key Point

  • Warfarin and low-molecular-weight heparin are considered safe for use by women requiring anticoagulant therapy who wish to breastfeed.

This content is excerpted from MKSAP 17 with permission from the American College of Physicians (ACP). Use is restricted in the same manner as that defined in the MKSAP 16 Digital license agreement. This material should never be used as a substitute for clinical judgment and does not represent an official position of ACP. All content is licensed to on an “AS IS” basis without any warranty of any nature. The publisher, ACP, shall not be liable for any damage or loss of any kind arising out of or resulting from use of content, regardless of whether such liability is based in tort, contract or otherwise.

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