Venous thromboembolism in the morbidly obese.

Obesity has been considered as a high risk factor in the development of thromboembolism. To test the validity of this hypothesis, the records of 564 morbidly obese patients who underwent gastric bypass for control of their obesity were reviewed. Four patients, 0.7 per cent, had proved fatal pulmonary emboli and three demonstrated detectable, but not fatal, embolization. Fifty-seven patients were studied prospectively with Doppler examinations of the lower extremities, and only one patient had a transient abnormality of venous thrombosis of the calf, which proved to be associated with a nonfatal pulmonary embolus. The morbidly obese patients are not at high risk from thromboembolism, and the prophylactic use of low dose heparin, which may increase known wound morbidity, is discouraged. Doppler ultrasound of the lower extremities, however, has proved usefulness to differentiate deep venous thrombosis of the lower extremity from other causes of pain in the leg of the morbidly obese.