Postoperative venous thrombosis. Evaluation of five methods of treatment.

Five methods for preventing deep venous thrombosis in postoperative patients were evaluated and compared with a control group. Five hundred patients from five surgical specialties were studied. The incidence of deep venous thrombosis was 37.3 percent in the control group but significantly less within all treatment groups. The minidose heparin group had the highest incidence (26.9 percent) because there were a large number of bilateral thromboses. The antistasis modalities did slightly better than the drugs; the intermittent pneumatic compression group had the fewest thromboses (11.9 percent). The significant risk factors for postoperative deep venous thrombosis are (1) obesity, (2) malignancy, (3) a history of venous disease, major surgery or major fracture, (4) length of surgery greater than 1 hour, and (5) increasing age. Four nonfatal pulmonary emboli occurred in 500 patients. Two were in women with hysterectomies in whom thrombosis had never been detected in an extremity; it is presumed that these clots arose from pelvic veins. It is thus recommended that patients in these high risk groups be treated prophylactically with one of the aforementioned modalities to decrease the risk of postoperative deep venous thrombosis. Of the different methods used to detect deep venous thrombosis, iodine-125 fibrinogen scanning was superior to both impedance plethysmography and venous Doppler ultrasound. One hundred percent of the thrombi were identified with scanning, whereas far fewer were detected with the latter methods. It is recommended that fibrinogen scanning be used clinically in patients in high risk categories who are undergoing major operative procedures.