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  • Virchow's triad: Stasis, vascular injury, hypercoagulability

    • -Stasis: Venous insufficiency, heart failure, prolonged bed rest/plane travel

      -Endothelial injury: Direct trauma, chemotherapy infusion, previous DVT, phlebitis, operative trauma all increase release of tissue factor increasing thrombin and decreasing fibrinolysis

      -Hypercoagulability: Malignancy, protein C or S deficiency, disseminated intravascular coagulation (DIC), liver failure, elevated homocysteine, factor V Leiden, prothrombin gene variant, paroxysmal nocturnal hemoglobinuria

    • Important risk factors

    • -Recent surgery

      -Trauma

      -Cancer

      -Prolonged immobilization

      -Oral contraceptive use

    • Other risks

    • -Advanced age

      -Type A blood group

      -Obesity

      -Prior DVT

      -Multiparity

      -Inflammatory bowel disease

      -Systemic lupus erythematosus

    • Most common in calf veins, may arise in femoral or iliac

    • 25% calf DVT progress proximally

    • Proximal DVT (femoral or iliac)

    • -Chronic venous insufficiency, 25%

      -Fatal pulmonary embolism (PE), 10%

    • Phlegmasia cerulea dolens caused by iliofemoral venous thrombosis, which is characterized by cyanosis of limb from venous outflow obstruction; potentially limb-threatening

    • In phlegmasia alba dolens, leg is pulseless, pale, cool; potentially limb-threatening

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Epidemiology

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  • • Affects 500,000 persons in United States each year

    • Up to 21% mortality in elderly

    • 20-30% of new DVT have occult malignancy (lung, pancreas, prostate, breast, ovary most common)

    • Surgery increases risk 21-fold

    • Complication rates

    • -General surgery, 20%

      -Neurosurgery, 24%

      -Hip/knee arthroplasty, 50%

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Symptoms and Signs

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  • • 50% are asymptomatic

    • Thigh or calf pain with or without edema

    • Extensive DVT

    • -Massive edema

      -Cyanosis

      -Dilated superficial veins

    • Low-grade fever, tachycardia

    • 50% have positive Homans sign (calf pain with ankle dorsiflexion)

    • Acute PE

    • Phlegmasia

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Imaging Findings

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  • Duplex US

    • -Sensitivity/specificity > 95%

      -Evaluate vein for flow, dilation, and incompressibility (indicate clot present)

      -Acute clot anechogenic, chronic clot echogenic

      -Less accurate to detect calf thrombosis

    Magnetic resonance venography (MRV)

    • -Sensitivity/specificity nearly 100%

      -Gadolinium MRV for thrombus age

    D-dimer levels

    • -Too nonspecific

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Rule Out

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  • • Local muscle strain

    • Achilles tendon rupture

    • Cellulitis

    • Lymphedema

    • Baker cyst obstructing popliteal vein

    • Retroperitoneal mass (obstructing iliac vein)

    • Congestive heart failure (CHF), liver, kidney failure, inferior vena cava (IVC) obstruction (bilateral edema)

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  • • Duplex US

    • Consider hypercoaguable work-up if idiopathic

    • CT scan thorax with pulmonary embolus-specific protocol

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  • • Goal is to reduce complications

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Anticoagulation

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  • • Primary treatment

    • Decreases recurrence and PE risk by 80%

    • Limits propagation of clot (no effect on clot lysis)

    • Iliofemoral thrombosis

    • -Thrombolytic therapy

      -Surgical thrombectomy

    • IVC filter is contraindication to anticoagulation

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Surgery

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Indications

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  • • Calf compartment syndrome

    • Massive extremity edema

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Medications

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Heparin

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  • • Potentiates antithrombin III, inhibits thrombin

    • Partial thromboplastin time (PTT) goal of 2 times normal

    • Effective heparinization within 24 hrs decreases risk of DVT recurrence

    • ...

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