Embolization during treatment of deep venous thrombosis: incidence, importance, and prevention.

The standard of care for the treatment of acute deep venous thrombosis (DVT) is anticoagulation, which often prevents the formation of new thrombus and reduces the risk of pulmonary embolism (PE) but fails to eliminate the clot burden. Patients who have thrombus remaining in their deep venous system despite therapeutic anticoagulation are at high risk for developing symptoms of the postthrombotic syndrome, a debilitating condition that adversely affects their quality of life. Strategies of thrombus removal for acute DVT, such as operative thrombectomy, catheter-directed thrombolysis, and pharmacomechanical techniques, are designed to avoid postthrombotic morbidity by restoring patency to the deep veins, but there is concern that these techniques may result in fragmentation of clot and pulmonary embolization. Careful patient evaluation before treatment is essential for preventing complications and often reveals asymptomatic pulmonary emboli in as many as 50% of patients. Nonobstructive or free-floating thrombus in the vena cava is a risk factor for procedure-related embolization and is frequently an indication for the use of vena caval filtration. A review of the literature on acute DVT treated by anticoagulation alone or with strategies of thrombus removal reveals that pulmonary embolization is an infrequent occurrence. Treatment with anticoagulation alone, however, increases the risk of patients developing symptoms of the postthrombotic syndrome, whereas thrombus removal strategies reduce postthrombotic morbidity without increasing the risk of embolization.