Re-evaluation of the role of impedance plethysmography in the diagnosis of deep vein thrombosis in surgical patients.

The clinical diagnosis of deep-vein thrombosis (DVT) is nonspecific and nonsensitive. As a result invasive and non-invasive laboratory tests are needed. In order to detect the diagnostic value of impedance plethysmography (IPG), a widely used non-invasive laboratory test, a prospective clinical trial was performed to compare IPG with color Doppler-ultrasonography (CDUS) and venography. Seventy-six (41 female, 35 male) high-risk abdominal surgery patients were included in the study. IPG and CDUS were performed preoperatively. During the postoperative period IPG, CDUS and venography were carried out. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of IPG were all determined. The preoperative IPG was positive in 32 patients, being (+) in 29 patients postoperatively. On the other hand, two of the 29 postoperative IPG (+) patients had DVT diagnosed postoperatively by CDUS and venography. One of 47 IPG (-) patients had DVT diagnosed postoperatively. According to these findings, the sensitivity of IPG was 67%, specificity 63%, and PPV, NPV and accuracy were 7%, 98% and 63%, respectively. Our study showed that IPG was not a reliable non-invasive laboratory method in the diagnosis and screening of DVT of the lower extremity.