Lower-Extremity Venous Thrombosis:C

Lower-Extremity Venous Thrombosis:Comparison of Venography 9 Impedance Plethysmography* and Intravenous Manometry This study was undertaken to compare impedance plethysmography with lower-extremity venography and venous manometry in the diagnosis of acute deep venous thrombosis(DVT)of the lower extremity.Ninety-six extremities were studied.In this population, in which the prevalence of acute DVT was 43.8%, plethysmography had a sensitivity of 86.8% and a specificity of 72.0%.The predictive value of abnormal findings at plethysmography was 70.2%, and the predictive value of normal findings at plethysmography was 87.8%.Venous manometry was performed successfully in 89 extremities.A statistically significant difference was shown in the mean intravenous pressure between patients with and without acute DVT.However, there was considerable overlap between the two populations, limiting the predictive value of impedance plethysmography in any given patient.Index terms:Extremities, angiography, 935.124 • Extremities, thrombosis, 935.751 • Plethysmography, 935.1299 • Veins, extremities, 935.7511 From the Department of Diagnostic Radiology(J.F.C., A.T.Y., T.P.S., M.D.D., D.W.H., W.R.C.Z., K.A.)and the Noninvasive Vascular Laboratory(D.K., D.N.), University of Minnesota Hospital and Clinic, Minneapolis.From the 1985 RSNA annual meeting.Received November 26, 1985; revision requested January 20, 1986; revision received March 24, 1988; accepted April 4.Address reprint requests to K.A., Box 292 UMHC, 420 Delaware St SE, Minneapolis, MN 55455.® RSNA, 1988See also the articles by Naidich et al(pp 97100), Cronan et al(pp 101-107), and Redman(pp 277-278)in this issue.THE role of noninvasive examinations for the exclusion of acute deep venous thrombosis(DVT)of the leg is not clearly established, and both good and bad results have been reported(1-6).We studied the correlation between venography, impedance plethysmography, and venous manometry in the diagnosis or exclusion of acute DVT in a mixed patient population including inpatients and outpatients.Ninety-six lower extremities in 76 patients were examined with venography, impedance plethysmography, and manometry.During a 2-year period, the patients were referred for suspected DVT from outpatient clinics, the emergency room, and inpatient stations at the University of Minnesota Hospital and Clinic.Selection of patients was biased since only patients referred to exclude DVT were included in the study.Patients referred for other reasons were excluded.Twenty-three of 76 patients(30.3%)were outpatients at the time of referral.The 53 inpatients(69.7%)were referred from medical(including oncology), surgical, and rehabilitation services.