Pulmonary embolism

Pulmonary embolism is about 5 times more common in pregnant women than in similarly aged nonpregnant women, but is still relatively infrequent (about 0.1% of pregnancies). The increased risk is related to changes in coagulation factors related to pregnancy, to local obstruction of veins by the uterus, and trauma to veins during delivery.

Diagnosis of a DVT can be made by ultrasound, and will require similar treatment to a pulmonary embolism. Both ventilation-perfusion (V/Q) scans and CT angiograms are used in pregnancy to diagnose pulmonary embolism, the latter being more common. V/Q is useful in the woman with a allergy to intravenous contrast. Radiation risk to the fetus from CT angiogram is minimal, with appropriate precautions and screening of the abdomen. V/Q scan radiation exposure can be reduced by beginning with a perfusion scan using half the dose (and avoiding the ventilation component if this is normal)

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Treatment is with low molecular weight heparin (LMWH), preferably using a weight-adjusted dosing regimen, and/or titrating to anti-factor X levels. Treatment should be for a minumum of 3 months, and for at least 6 weeks postpartum. LMWH should be held for 24 hr prior to delivery or epidural/spinal anesthesia. Warfarin is not used during pregnancy, but is safe during lactation. Thrombolytic therapy has been used in pregnancy, when clinically indicated.

References:

Miller MA, Chalhoub M, Bourjeily G. Peripartum pulmonary embolism. Clin Chest Med. 32(1):147-64, 2011

Scarsbrook AF, Gleeson FV. Investigating suspected pulmonary embolism in pregnancy. BMJ. 2007;334:418-9.

Ginsberg JS, Greer I, Hirsh J: Use of antithrombotic agents during pregnancy. Chest 119(Suppl 1):122S–131S, 2001.

Bates SM, Greer IA, Middeldorp S, Veenstra DL, Prabulos A-M, Vandvik PO. VTE, Thrombophilia, Antithrombotic Therapy, and Pregnancy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 141(2_suppl):e691S-e736S, 2012

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