Epidemiology and etiopathogenesis of deep venous thrombosis of the lower limbs
Bounameaux, H.
Agressologie Revue Internationale de Physio-Biologie et de Pharmacologie Appliquees Aux Effets de l'Agression 31(3): 141-143
1990
ISSN/ISBN: 0002-1148 PMID: 2240406 Document Number: 361282
Deep venous thrombosis and its complication pulmonary embolism are responsible for more than 50,000 deaths annually in the US, 2/3 of which occur postoperatively. Nearly 75% of such deaths could be avoided by adequate prophylaxis. All forms of surgery entail some risk of deep venous thrombosis, ranging from 10% after endoscopic prostate resection to over 50% for total hip replacement. 1.6 of thromboses will embolize and 1/4 of pulmonary emboli are fatal. The goal of prevention is to decrease the incidence of fatal pulmonary emboli while limiting the risks related to prevention. A secondary goal is to reduce the frequency of postthrombotic syndrome, a late complication of deep venous thrombosis which frequently causes invalidism. A preoperative evaluation of risks of deep venous thrombosis and of the likelihood of bleeding problems should be followed by selection of appropriate preventive measures. The evaluation should be repeated postoperatively, taking into account such factors as the duration of the intervention, the diagnosis, and the predicted duration of bed rest. Evaluation of the risk of deep venous thrombosis requires knowledge of its etiopathogenesis. Deep venous thrombosis results from a multifactorial process involving venous stasis, lesion of the vascular wall, and anomalies of blood composition. All the clinical risk factors for deep venous thrombosis are related to 1 or more of these elements. Risk factors related to stasis include immobilization, postoperative or postpartum status, pregnancy, and Cockett's syndrome. Risk factors related to lesions of the vascular wall include hip surgery, trauma, age, sepsis, varices and obesity, and postthrombotic syndrome. Risk factors related to blood anomaly include postoperative status, pregnancy, oral contraceptive use, cancer, nephrotic syndrome, hypercoagulability, trauma, and heredity. The most common clinical risk factors for deep venous thrombosis are age, surgical intervention, trauma, burns, cancer, pregnancy and delivery, oral contraceptive use, varices, obesity, and postthrombotic syndrome. The relative risk of deep venous thrombosis among OC users is 4.0 overall and higher for those with type A blood. The pathogenic mechanisms are similar to those of pregnancy except that the fibrinolytic capacity is not change. The principal mechanism is perhaps the declining level of antithrombin III, observed with estrogens and some progestins. Among methods of prevention are different forms of compression, use of heparin alone or in combination with other drugs, and oral anticoagulants.