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Deep Venous Thrombosis

Fifty percent of venous thrombi of the lower extremity will embolize to the lung if not treated. The source of symptomatic pulmonary emboli is usually thrombosis in the larger veins above the knee rather than thrombosis in the veins of the calf. Deep venous thrombosis can be found in at least 80% of patients with a pulmonary emboli trombosis, blood clot, phlebitis, flebitis

Risk Factors

Venous Stasis risk factors include prolonged immobilization, stroke, myocardial infarction, heart failure, obesity, varicose veins, anesthesia, age >65 years old.

Endothelial Injury risk factors include surgery, trauma, central venous access catheters, pacemaker wires, previous thromboembolic event (especially if precipitating factors are

Hypercoagulable State risk factors include malignant disease, high estrogen level (pregnancy, oral contraceptives).

Hematologic Disorders. Polycythemia, leukocytosis, thrombocytosis, antithrombin III deficiency, protein C deficiency, protein S deficiency, antiphospholipid syndrome, inflammatory bowel disease, deep vein thrombosis, leg clot.

Signs and symptoms of DVT are absent in about 50%, and they range from subtle to obvious. The disorder may be asymptomatic, or the patient may complain of pain, swelling, "heaviness," aching, or the sudden appearance of varicose veins. Risk factors may be absent. DVT may manifest as a unilaterally edematous limb with calf pain a erythrocyanotic appearance, dilated superficial veins, elevated skin temperature, calf pain tenderness in the thigh or calf. Absence of clinical signs does not preclude the diagnosis. A swollen, tender leg with a palpable cord in the popliteal fossastrongly suggests popliteal DVT. Marked discrepancy in limb circumference supports the diagnosis of DVT, but most patients do not have measurable swelling. The clinical diagnosis of DVT is correct only 50% of the time; therefore, diagnostic testing is mandatory when DVT is suspected.

Diagnostic Testing

Duplex Scanning

When Doppler measurement of blood flow is added to ultrasound imaging, the combination is referred to as a duplex scan.

Doppler Studies: Uses Doppler shifts to detect blood flow in the veins.

Ultrasound Imaging. Two-dimensional ultrasonography produces an image of the