Routine duplex ultrasound screening after TKA is not necessary

We determined if negative ultrasound screening at the time of acute care hospital discharge or 2 weeks post operatively would reliably identify patients without deep venous thrombosis, thus allowing discontinuation of warfarin chemoprophylaxis. Patients undergoing primary TKA (1344) were treated with adjusted-dose warfarin (target prothrombin time, 15-18 seconds; internationalized normalization ratio, 1.4-1.7) until screening and then aspirin (325 mg po bid) until 6 weeks postoperatively. Deep venous thrombosis as determined by ultrasound was the measured outcome. From 1994 to 1997, 525 patients underwent screening ultrasound before discharge (usually postoperative Day 3): 12 (2.3%) patients with proximal deep venous thrombosis and three (0.6%) patients with distal deep venous thrombosis were identified. From 1997 to 2001, 819 patients underwent ultrasound screening at Day 14 postoperatively: 10 (1.2%) patients with proximal deep venous thrombosis and 29 (3.6%) patients with distal deep venous thromboses were identified. There was no difference in proximal deep venous thrombosis detection, but there was a difference in distal deep venous thrombosis detection. We no longer screen asymptomatic patients with ultrasound for deep venous thrombosis after TKA.