Thrombosis, Venous (Phlebothrombosis, Thrombophlebitis)

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- An abnormal vascular condition in which a thrombus develops in a vein. Thrombophlebitis refers to a thrombus accompanied by inflammation of the vein (phlebitis). Phlebothrombosis refers to a thrombus with minimal inflammation. Dislodgment and migration of a thrombus are known as thromboembolism.

Causes and Incidence A number of factors acting in concert contribute to thrombus formation, including intimal damage to the vein from indwelling catheters, injection of irritating substances or septic phlebitis; hypercoagulability related to underlying disorders (idiopathic thrombocytopenia purpura, malignancies, blood dyscrasias) and use of oral contraceptives; and stasis from prolonged immobilization or postpartum or postoperative states. Venous thrombosis is the most commonly seen venous disorder except for varicose veins. Individuals at greatest risk are postoperative patients and those receiving IV therapy.

Disease Process Most thrombi begin forming in the valve cusps of deep calf veins. Tissue thromboplastin is released and forms thrombin and fibrin that trap RBCs to form a clot. The clot continues to enlarge until it eventually occludes the lumen of the vessel. It may break off and migrate to the systemic circulation.

Symptoms

Deep veins
Calf pain and tenderness; positive Homans’ sign (calf pain on foot dorsiflexion); dilated superficial veins; edema, increased size of involved extremity; redness and warmth over vein site

Superficial veins
Redness, warmth, and tenderness over affected vein, which is visible and palpable

Potential Complications Chronic venous insufficiency and pulmonary embolus are the most common complications of thrombosis.

Diagnostic Tests A physical examination is the primary diagnostic tool in detecting venous thrombosis and in distinguishing arterial from venous obstructions. Noninvasive tests include ultrasonography and plethysmography, which show reduced blood flow. Contrast venography is the most accurate and the confirmatory diagnostic tool.

Treatments

Surgery
Ligation, clipping, plication, and thrombectomy when thrombosis fails to respond to conservative therapy; extravascular vena cava interruption with possible placement of intracaval filter when emboli are probable.

Drugs
Superficial: nonsteroidal antiinflammatory drugs for pain and inflammation Deep vein: fibrinolytics to lyse clots; anticoagulants (heparin for acute treatment, warfarin for maintenance) to augment thrombolysis; antiplatelets to prevent thrombus formation; analgesics (aspirin is contraindicated because it interferes with platelet function).

General
Superficial: moist compresses to treat discomfort Deep vein: bed rest with elevation of affected extremity above the level of the heart; warm, moist packs; antiembolism hose when ambulatory; monitoring of prothrombin time and partial thromboplastin time during anticoagulant therapy; monitoring for signs of pulmonary embolus; instruction about bleeding precautions while undergoing anticoagulants.

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