Clinical Approach

DVT occurs in slightly less than 1 % of pregnancies. The pregnant state increases the risk fivefold due to the venous stasis with the large gravid uterus pressing on the vena cava and the hypercoagulable state due to the increase in clotting factors. Cesarean delivery further increases the risk of DVT. Whereas clots involving the superficial venous system pose virtually no danger and can be treated with analgesia, DVT is associated with pulmonary embolism in 40% of untreated cases. The risk of death is increased tenfold when pulmonary embolism is unrecognized and untreated. Therefore, early diagnosis and anticoagulation treatment are crucial.

Signs and symptoms of DVT include "muscle pain," deep linear cords of the calf, and tenderness and swelling of the lower extremity. A 2-cm difference in leg circumferences is sometimes helpful. Unfortunately, none of these findings are very specific for DVT; in fact, the examination is normal in half of DVT cases. Hence, imaging tests are necessary for confirmation.

In pregnancy, the diagnostic test of choice is Doppler ultrasound imaging, usually with a 5- to 7.5-MHz Doppler transducer to measure venous blood flow with and without compression of the deep veins. This modality is nearly as sensitive and specific as the time-honored method of contrast venography.

Management of DVT is primarily anticoagulation with bed rest and extremity elevation. During pregnancy, heparin usually is preferable to warfarin (Coumadin), because Coumadin may cause congenital abnormalities and is more difficult to reverse. Heparin, which is a potent thrombin inhibitor that blocks conversion of fibrinogen to fibrin, combines with antithrombin III. It stabilizes the clot and inhibits its propagation. After full intravenous anticoagulation therapy for 5 to 7 days, the therapy is generally switched to subcutaneous therapy to maintain an activated partial thromboplastin time at 1.5 to 2.5 times control for at least 3 months after the acute event. After 3 months, either full heparinization or "prophylactic heparinization" can be used for the remainder of the pregnancy and for 6 weeks postpartum (see Case 22).

Comprehension Questions

[37.1] Which of ihe following is a reason for the hypercoagulable state in pregnancy?

A. Venous stasis

B. Deceased clotting factors levels

C. Elevated platelet count

D. Endothelial damage

[37.2] Long-term heparin therapy may lead to which of the following?

A. Osteoporosis

B. Thrombophilia

C. Fetal intracranial hemorrhage

D. Diabetes mellitus

[37.3] Which of the following is the most common location of a deep venous thrombosis after gynecologic surgery?

A. Inferior vena cava

B. Lower extremities

C. Ovarian vein

D. Superior vena cava

E. Subclavian vein

[37.4-1 After a woman develops a deep venous thrombosis during pregnancy, which of the following agents most likely is contraindicated?

A. Medroxyprogesterone acetate depot (Depo-Provera) contraception

B. Intrauterine contraceptive device (IUD)

C. Combination oral contraceptive

D. Levonorgestrel silastic implants (Norplant)

E. Prostaglandin compounds


[37.1] A. Venous stasis is present due to the uterus compressing the vena cava. Usually, the platelet count is slightly lower in the pregnant state. The lower limit of normal is 150,000/mm3 in the nonpregnant patient and 120,000/mm3 in the pregnant woman.

[37.2] A. Heparin is a large, charged glycoprotein that does not cross the placenta very well. Osteoporosis and thrombocytopenia are long-term complications.

[37.3] B. The most common locations of DVT associated with gynecologic-surgery are the lower extremities and the pelvic veins.

[37.4] C. The estrogen in the combination oral contraceptive is slightly thrombogenic and may be contraindicated in a woman with a prior DVT.

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