Combined Use of Leg Scanning and Impedance Plethysmography in Suspected Venous Thrombosis

Abstract

Venography is the standard method for the diagnosis of venous thrombosis but is invasive and may cause discomfort. We evaluated the combination of impedance plethysmography and 125I-fibrinogen leg scanning as an alternative to venography in 200 symptomatic patients. One or both of these less invasive tests was positive in 81 of 86 patients with positive venograms (sensitivity of 94 per cent) and both were negative in 104 of 114 patients with negative venograms (specificity of 91 per cent). These two tests detected all 60 patients with popliteal or more proximal venous thrombosis and 21 of 26 patients with calf-vein thrombosis. In addition, this approach detected 21 of 22 patients with calf-vein thrombosis with symptoms for eight days or less. These results suggest that the combination of these two less invasive tests can be used as an alternative to venography in selected patients with clinically suspected venous thrombosis.

Ultrasonography and Diagnosis of Venous Thromboembolism

“…Before the acceptance and widespread use of venous duplex scanning, impedance plethysmography (IPG) was employed as the initial noninvasive test for patients with suspected acute lower extremity DVT. [3][4][5][6] According to studies that compare IPG to venography and exclude clinical outcome, its sensitivity for proximal DVT ranges around 65%. 7-8 IPG may not detect nonocclusive proximal DVT or occlusive proximal DVT present in parallel venous systems, such as duplicated femoral or popliteal veins, and cannot detect DVT isolated to the calf veins.…”

Diagnosis of deep vein thrombosis, an overview

“…In only 30-60% of patients with clinically sus pected DVT the diagnosis is confirmed by CV [3,4,7,8,[10][11][12][13][14][15][16][22][23][24]. The reason for the inaccu racy of the clinical diagnosis is that none of the signs and symptoms is unique and many other disorders can mimic DVT such as superficial phlebitis, trauma, postthrombotic syndrome, erysipelas, oedema due to congestive heart fail ure, external venous compression due to malig nancy, burst Bakers' cyst, muscle tear, lymphangi tis, lymphoedema and cellulitis.…”

“…Conse quently an abnormal test result justifies the initia tion of anticoagulant treatment. Its sensitivity in calf vein thrombosis is considerably less (20%) because venous outflow may be possible through other patent calf veins; its specificity remains high at about 95% [16,[42][43][44][45][46][47][48][49],…”

“…firmed by venography [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This implies that for years patients with clinical signs of DVT were diagnosed incorrectly and challenged unnecessar ily to the side-effects of anticoagulants with high costs of admission [19].…”

Impedance plethysmography: the relationship between venous filling and sensitivity and specificity for proximal vein thrombosis.

“…[1][2][3][4][5][6] This technique quantitates the capacity of the venous system to fill and empty in response to temporary venous outflow obstruction."' I These changes in venous volume are influenced by a number of physiological determinants, including the anatomic capacity of the venous system, venous tone, venous pressure and venous distensibility.7'8 Volume changes are also influenced by pathological determinants, including reduced arterial inflow, increased central venous pressure and thrombotic or non-thrombotic obstruction of the proximal veins."'…”