Deep vein thrombosis: prophylaxis, diagnosis, and treatment--lessons from orthopedic studies

Abstract

Orthopedic surgery patients are at high risk of developing thromboembolic disease simply by the very nature of the procedures they undergo even if no other risk factor is present. In unprotected total hip replacement patients, the incidence of fatal pulmonary embolism is at least 2% and the incidence of deep vein thrombosis reaches 50%. Noninvasive screening methods for deep vein thrombosis such as cuff impedance phlebography and fibrinogen scanning have been proved accurate in patients with suspected symptomatic deep vein thrombosis. In asymptomatic but high-risk total hip replacement patients, however, these methods have a combined sensitivity of only 23%. Radiological venography still remains the screening method of choice in these patients. Low-dose warfarin prophylaxis reduces the incidence of deep vein thrombosis to 16% and lowers the risk of major bleeding complications tenfold over the traditional higher dose warfarin. It also enhances protection against proximal thrombi compared to dextran, aspirin, or external pneumatic compression. When low-dose warfarin is used for 12 weeks after total hip replacement without routine venography, it drastically reduces fatal pulmonary embolism (no cases in 268 consecutive patients). This prophylactic regimen is also safe in terms of bleeding complications before and after patient discharge. Finally, it is very cost effective: a saving of $176,000 in treating 268 patients compared with routine venography.