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Thromboembolic Disorders During Pregnancy


Lara A. Friel

, MD, PhD, University of Texas Health Medical School at Houston, McGovern Medical School

Reviewed/Revised Nov 2023

In thromboembolic disorders Blood Clots After Delivery The risk of developing blood clots (thrombophlebitis) is increased for about 6 to 8 weeks after delivery (see Thromboembolic Disorders During Pregnancy). Typically, blood clots occur in the... read more , blood clots (thrombi) form in blood vessels. An embolus is a blood clot that travels through the bloodstream and blocks an artery. In the United States, thromboembolic disorders are a common cause of death in pregnant women.

The risk of developing a thromboembolic disorder is increased for about 6 weeks after delivery. Most complications due to blood clots result from injuries that occur during delivery. The risk is much higher after cesarean delivery than after vaginal delivery.

Deep vein thrombosis may also develop in the pelvis. There, it may not cause symptoms. A clot can move from the deep veins of the legs or pelvis to the lungs. There, the clot may block one or more lung (pulmonary) arteries. This blockage, called pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more , can be life threatening.


  • Doppler ultrasonography to check for blood clots in the legs

  • Computed tomography to check for pulmonary embolism

During pregnancy, if women have symptoms suggesting a blood clot, Doppler ultrasonography (used to evaluate blood flow) may be done to check the legs for clots.

If the diagnosis of pulmonary embolism is still uncertain, a procedure called pulmonary angiography (angiography of the lung's blood vessels) is required. For this procedure, doctors make a small incision, typically in the groin but sometimes in the arm. Then they insert a thin, flexible tube (catheter) and thread it through blood vessels to an artery in a lung. When the catheter is in place, a radiopaque contrast agent is injected through the catheter to outline the blood vessels in the lungs, and x-rays are taken.

After the baby is delivered, doctors may use CT with a contrast agent to check women for blood clots in the pelvis.


  • Heparin during pregnancy and sometimes after delivery

  • Warfarin after delivery

If a blood clot is detected, heparin (an anticoagulant, a drug that inhibits blood clotting) is started without delay. Heparin may be injected into a vein (intravenously) or under the skin (subcutaneously). Heparin does not cross the placenta and cannot harm the fetus. Treatment is continued for 3 to 6 months. Then, to prevent new blood clots from forming, doctors give the woman heparin at a lower dose for at least 6 weeks after delivery. During this time, the risk of blood clots remains high.

After delivery, warfarin may be used instead of heparin, particularly if women require treatment for more than 6 to 8 weeks. Warfarin can be taken by mouth, has a lower risk of complications than heparin, and can be taken by women who are breastfeeding.

Women who have had a blood clot during a previous pregnancy or who had a thromboembolic disorder before they became pregnant may be given heparin during each pregnancy and for 6 weeks after delivery to prevent blood clots from forming.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Hepflush-10 , Hep-Lock, Hep-Lock U/P, Monoject Prefill Advanced Heparin Lock Flush, SASH Normal Saline and Heparin
Coumadin, Jantoven
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