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Pregnancy increases incidence of deep vein thrombosis and venous thromboembolic disease (0.5–2/1,000 pregnancies).


  • Incidence highest postpartum:
    • Increased 2- to 5-fold for deep vein thrombosis
    • Increased 15-fold for pulmonary embolism
  • Cesarean section increases risk even further:
    • Two-fold increase compared with vaginal delivery

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Risk Factors
Endothelial injury
  • Delivery of placenta results in large surge of procoagulants
  • Surgical intervention increases endothelial injury
  • Smoking (>1/2 ppd) may increase risk for endothelial injury
Changes in coagulation
  • Coagulation factors increase, protein S and C activity decreases, antifibrinolytics increase
  • Patients with inherited thrombophilias are at increased risk (factor V Leiden, protein S or C deficiency, AT-III deficiency, antiphospholipid antibody)
  • Chorioamnionitis may increase risk
Venous stasis
  • Compression by enlarged uterus (L > R)
  • Proximal and pelvic vein thrombosis more common
  • Obesity, bed rest, multiple gestation are additional risk factors
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Diagnostic Approach
  • Prior history of thromboembolic disease
  • Preexisting thrombophilias
Physical exam
  • Swelling of lower extremity is common in pregnancy
  • Left-sided thrombosis in >80% of cases
  • Dyspnea
  • Common during pregnancy and after Cesarean section
Radiographic evaluationVenous thrombosis in lower extremities and pelvisVenous compression Doppler USHighly sensitive and specific for proximal vein thrombosis
  • May help when Doppler US is equivocal
  • Suspected pelvic vein thrombus
Contrast venography“Gold standard,” seldom done
Pulmonary vasculatureV/Q scanSuperior test if CXR Normal
CT angiography
  • Test of choice with abnormal chest x-ray
  • If V/Q scan is equivocal
  • Inadequate sensitivity for subsegmental emboli
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Indicated in all patients with
  • One or more episode of venous thromboembolism in the past
  • Antiphospholipid syndrome
  • Homozygous prothrombin mutation
  • Homozygous factor V Leiden mutation
  • Coexisting heterozygosity for prothrombin and factor V Leiden mutations
  • Hyperhomocysteinemia
  • Protein S deficiency
  • Protein C deficiency
Cesarean section in patients with no additional risk factors is not an indication for thromboprophylaxis
One risk factorGraduated compression stockings or pneumatic compression device or pharmacologic thromboprophylaxis
Multiple risk factorsGraduated compression stockings or pneumatic compression device and pharmacologic thromboprophylaxis
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Pharmacologic Thromboprophylaxis
  • Enoxaparin 40 mg q day or BID
  • Dalteparin 5,000 U Q day or BID
  • Tinzaparin 4,500 U Q day
Some recommend therapeutic doses in patients with past history of multiple DVT
Heparin (unfractionated; SQ)
  • 5,000 U BID
  • Adjusted dose: start with 5,000 U BID and titrate to anti-Xa activity (therapeutic if anti-Xa is 0.1–0.3 U/mL); usual range is 5,000–10,000 U twice daily. Measure anti-Xa 6 h after every other dose
Some recommend therapeutic doses in patients with past history of multiple venous thromboembolism
  • Start after heparin; overlap for at least 5 days
  • Therapeutic range: INR 2–3
Warfarin does not get excreted in breast milk in significant amounts

  • Usually started 6 hours after Cesarean delivery unless there is concern for ongoing ...

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