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 t hrombosis, for monitoring of potential propagation of deep venous thro mbosis 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 modali ty as well as with venography after a total hip or total knee arthropl asty. Compared with venography, duplex ultrasonography demonstrated 10 0 per cent sensitivity, specificity, and accuracy for the detection of proximal deep venous thrombosis and 88 per cent sensitivity, 98 per c ent 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 pneuma tic stockings and aspirin for prophylaxis against deep venous thrombos is 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 veno us thrombosis in twenty-two patients; all twenty-nine patients were as ymptomatic. The patients who had distal deep venous thrombosis had sur veillance with serial duplex ultrasonography on the seventh and fourte enth postoperative days; five of these patients were found to have had propagation of the thrombosis to the proximal deep veins. Proximal de ep venous thrombosis, found on duplex screening, or propagation of the thrombosis from distal to proximal, found on serial surveillance, war ranted 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 pati ents who were seen to have a stable distal deep venous thrombosis on s erial duplex surveillance were followed clinically for a minimum of th ree months postoperatively; they remained asymptomatic for thromboembo lic disease. The final rate of deep venous thrombosis (before anticoag ulation) was twenty-nine of 100 patients, with twelve having a proxima l deep venous thrombosis and seventeen, a distal deep venous thrombosi s; all twenty-nine were asymptomatic. One patient who had a proximal d eep venous thrombosis, detected on duplex screening on the fourth post operative day had a non-fatal pulmonary embolism on the fifth postoper ative day. Duplex ultrasonography allowed fewer patients to have antic oagulation therapy, by confirmation of the absence of proximal deep ve nous thrombosis or the stability of distal deep venous thrombosis in e ighty-eight of the 100 patients. It also demonstrated the effectivenes s of prophylaxis and treatment of deep venous thrombosis by confirmati on of the absence or the resolution of deep venous thrombosis in all 1 00 patients.