POSTOPERATIVE SURVEILLANCE FOR DEEP VENOUS THROMBOSIS WITH DUPLEX ULTRASONOGRAPHY AFTER TOTAL KNEE ARTHROPLASTY

Duplex ultrasonography of the lower extremity was used for routine non-invasive screening for asymptomatic proximal and distal deep venous thrombosis, for monitoring of potential propagation of deep venous thrombosis from distal to proximal, and for confirmation of the resolution of proximal deep venous thrombosis after treatment. In the first part of the study, to substantiate the accuracy of duplex ultrasonography, 130 lower limbs (seventy-nine patients) were studied with that modality as well as with venography after a total hip or total knee arthroplasty. Compared with venography, duplex ultrasonography demonstrated 100 per cent sensitivity, specificity, and accuracy for the detection of proximal deep venous thrombosis and 88 per cent sensitivity, 98 per cent specificity, and 98 per cent accuracy for the detection of distal deep venous thrombosis. In the second part of the study, 100 patients who had had a total knee arthroplasty and had been managed with pneumatic stockings and aspirin for prophylaxis against deep venous thrombosis had screening of both lower extremities with duplex ultrasonography on the fourth postoperative day. Duplex ultrasonography demonstrated proximal deep venous thrombosis in seven patients and distal deep venous thrombosis in twenty-two patients; all twenty-nine patients were asymptomatic. The patients who had distal deep venous thrombosis had surveillance with serial duplex ultrasonography on the seventh and fourteenth postoperative days; five of these patients were found to have had propagation of the thrombosis to the proximal deep veins. Proximal deep venous thrombosis, found on duplex screening, or propagation of the thrombosis from distal to proximal, found on serial surveillance, warranted anticoagulation therapy in twelve asymptomatic patients; serial duplex ultrasonography was then used to confirm subsequent resolution of the proximal deep venous thrombosis. The seventy-one patients who had a negative result on duplex ultrasonography and the seventeen patients who were seen to have a stable distal deep venous thrombosis on serial duplex surveillance were followed clinically for a minimum of three months postoperatively; they remained asymptomatic for thromboembolic disease. The final rate of deep venous thrombosis (before anticoagulation) was twenty-nine of 100 patients, with twelve having a proximal deep venous thrombosis and seventeen, a distal deep venous thrombosis; all twenty-nine were asymptomatic. One patient who had a proximal deep venous thrombosis, detected on duplex screening on the fourth postoperative day had a non-fatal pulmonary embolism on the fifth postoperative day. Duplex ultrasonography allowed fewer patients to have anticoagulation therapy, by confirmation of the absence of proximal deep venous thrombosis or the stability of distal deep venous thrombosis in eighty-eight of the 100 patients. It also demonstrated the effectiveness of prophylaxis and treatment of deep venous thrombosis by confirmation of the absence or the resolution of deep venous thrombosis in all 100 patients.