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Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy

Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy is a topic covered in the 5-Minute Clinical Consult.

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Blood clots formed in the deep veins of the lower extremities (deep vein thrombosis [DVT]) or pelvis (iliac vein thrombosis) are at risk of traveling to the lung, causing a pulmonary embolism (PE).


  • Of venous thromboembolism (VTE) cases: DVT, 80%; PE, 20% (1)
  • 1.4 in 1,000 pregnancies, including 1.1 DVT and 0.3 PE in 1,000
    • Risk of VTE events is similar in all trimesters.
    • Highest risk postpartum, especially in first week
  • Leading cause of maternal death in developed countries—1.1 deaths per 100,000 deliveries

5 times greater risk than in nonpregnant population (1)

Etiology and Pathophysiology

Virchow triad (1)

  • Vascular injury: iliac vein injury during delivery
  • Venous stasis: progesterone-induced venous dilatation, compression on inferior vena cava (IVC) and iliac veins by gravid uterus
  • Hypercoagulability: ↑ coagulation factors (fibrin, factors II/VII/VIII/XI/X, von Willebrand factor [vWF]), ↓ fibrinolytic activity, and free protein S

Risk Factors

  • History of VTE (15–25% are recurrent cases)
  • Inherited or acquired thrombophilias
    • High risk: homozygous factor V Leiden (RR:34), homozygous prothrombin G20210A mutation (RR:26), the previous two combined mutation (RR:44) (1)
    • Low risk: heterozygous factor V Leiden (RR:8), heterozygous prothrombin G20210A (RR:7), antithrombin III (RR:5) deficiency, protein C (RR:5) or S (RR:3) deficiency. The relative risk is compared to all pregnancies (1); antiphospholipid syndrome (RR is uncertain) (2)
  • Age >35 years old
  • Obesity (BMI >30), smoking, parity ≥3
  • Medical comorbidities: heart and lung disease, SLE, sickle cell, IBD, nephrotic syndrome, T1DM
  • Obstetric risk factors include twin (and other multiple gestation), preeclampsia, cesarean section, prolonged labor (>24 hours), operative delivery, severe postpartum hemorrhage.
  • Transient and potentially recurring risk factors include assisted reproductive technology (ART), in vitro fertilization (IVF), ovarian hyperstimulation syndrome (OHSS), any surgery during pregnancy, hyperemesis, dehydration, bed rest >3 days, systemic infection, long distance travel (>4 hours).

Risk of VTE is higher in the postpartum period; interestingly, 2/3 of DVTs happen antepartum and 60% of PEs postpartum. Postpartum incidence of VTE is 10 to 20 times higher than in the nonpregnant state and is especially high after cesarean.

General Prevention

  • Screening for thrombophilias even after diagnosis of VTE during pregnancy is not recommended (2)[C].
  • Early mobilization, graduated compression stockings for low-risk groups
  • Antepartum thromboprophylaxis for high-risk thrombophilia with family history of VTE, ≥2 prior VTE (unprovoked, pregnancy, or estrogen related) (2). If no family history, suggest postpartum prophylaxis for 6 weeks only with prophylactic or intermediate dose low-molecular-weight heparin (LMWH) (2)[B].
  • Anticoagulation may not be required if prior VTE was not pregnancy related and associated with a risk factor no longer present.
  • Consider thromboprophylaxis for past single episode of idiopathic VTE, low-risk thrombophilia with past VTE, morbid obesity (BMI >40), bedridden patients, and assisted reproduction technologies (2)[C].
  • DVT prophylaxis both during and following cesarean delivery in the general population may be limited to pneumatic compression devices; however, in morbidly obese women (BMI ≥40), weight-based dosing of enoxaparin should be utilized postoperatively throughout the remainder of hospitalization (2)[B].

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Stephens, Mark B., et al., editors. "Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816908/all/Deep_Vein_Thrombosis_and_Pulmonary_Embolus_in_Pregnancy.
Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816908/all/Deep_Vein_Thrombosis_and_Pulmonary_Embolus_in_Pregnancy. Accessed April 18, 2019.
Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816908/all/Deep_Vein_Thrombosis_and_Pulmonary_Embolus_in_Pregnancy
Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 18]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816908/all/Deep_Vein_Thrombosis_and_Pulmonary_Embolus_in_Pregnancy.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Deep Vein Thrombosis and Pulmonary Embolus in Pregnancy ID - 816908 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816908/all/Deep_Vein_Thrombosis_and_Pulmonary_Embolus_in_Pregnancy PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -