Real-time ultrasound for the detection of deep venous thrombosis

Abstract

Accurate diagnosis of deep venous thrombosis (DVT) is a clinical problem in emergency practice. A prospective trial was conducted comparing real-time ultrasound with contrast venography in the diagnosis of proximal DVT. Seventy patients whose clinical presentations mandated diagnostic evaluation for DVT had real-time ultrasound of the involved leg followed by contrast venography. Initial readings of ultrasound and venography were compared with each other and with final readings to assess reliability of interpretation. Final ultrasound readings agreed with final venogram readings in all patients. Negative initial ultrasound readings agreed with final venogram readings in 56 of 56 patients (negative predictive value, 100%; 95% confidence interval, 94 to 100). Eighteen patients had positive initial ultrasound readings compared with 14 who had positive final venogram readings (positive predictive value, 78%; 95% confidence interval, 55 to 91). Negative real-time ultrasonography reliably excludes proximal DVT. Positive ultrasound reliably diagnoses proximal DVT only in experienced hands.