The Use Of Non-Invasive Testing And Venography For The Diagnosis Of Acute Recurrent Deep Vein Thrombosis

Abstract

Impedance plethysmography (IPG) combined with leg scanning is highly sensitive and specific for deep vein thrombosis (DVT) in patients with their first episode of clinically suspected DVT. This approach has not been evaluated in patients with suspected recurrent DVT. In this group of patients venography alone is of limited value in excluding acute DVT in the presence of previous DVT but is useful if constant intraluminal filling defects (ILFD) suggesting acute DVT are present. We have evaluated the clinical utility of IPG plus leg scanning and venography in 132 patients with clinically suspected acute recurrent DVT. If the IPG on referral was negative the patient was leg scanned daily for 72 hours and if both were negative, anticoagulant therapy was witheld. The validity and safety of this approach was tested by 3 months follow-up. If IPG was positive, venography was performed to distinguish ILFD’s from chronic DVT. If ILFD’s were detected, anticoagulant therapy was commenced. If no ILFD’s were detected the patient was leg scanned for 72 hours and if negative treatment was witheld. The clinical utility of this non-invasive approach is demonstrated by the results of this study. Of 132 patients, 82 (62%) were negative by both non-invasive tests and none died, developed pulmonary embolism or recurrent DVT during follow-up. The remaining 50 patients were positive by noninvasive testing; in 31 patients ILFD’s were detected and in 16 venography was indeterminate showing collaterals, absent segments, recanalization or inadequate visualization. The leg scan was positive in 10 of the latter 16 patients. Thus the diagnosis of recurrent acute DVT was established by the presence of ILFD’s or a positive leg scan. In 6 patients with a positive IPG, negative leg scan and indeterminate venogram the diagnosis remained uncertain. In conclusion this combined non-invasive and invasive approach provided definitive management in 126 of 132 patients (95%).