When the common femoral vein is revealed as flattened on spectral Doppler sonography: Is it a reliable sign for diagnosis of proximal venous obstruction?

OBJECTIVE. The purpose of the study was to determine if a monophasic waveform with no response to Valsalva's maneuver in the common femoral vein on spectral Doppler sonography is reliable for the diagnosis of proximal venous obstruction. SUBJECTS AND METHODS. In a prospective study from January 1993 through October 1995, 37 of 2138 cancer patients examined with duplex Doppler sonography exhibited monophasic flow in the common femoral vein on spectral Doppler imaging and no response to Valsalva's maneuver. These 37 patients were further evaluated with an abdominal and pelvic CT scan with IV contrast medium (n = 23); with sonography (n = 8), with MR imaging (n = 4), with venography (n = 1), or by both venography and CT (n = 1) to determine the cause of monophasic flow in the common femoral vein and lack of response to Valsalva's maneuver. All follow-up imaging studies were obtained from 0 to 30 days after initial duplex Doppler sonography. RESULTS. All patients with monophasic flow in the common femoral vein on spectral Doppler imaging and no response to Valsalva's maneuver had proximal venous extrinsic compression or deep venous thrombosis. Twenty-nine (78%) of 37 patients had extrinsic compression. Such compression was caused by pelvic masses in 15 (41%) of 37 patients, enlarged nodes in eight patients (22%), and postsurgical changes in six patients (16%). The remaining eight patients (22%) had proximal deep venous thrombosis. CONCLUSION. On spectral Doppler sonography, monophasic waveform with no response to Valsalva's maneuver in the common femoral vein is a dependable sign for the diagnosis of proximal extrinsic compression or deep venous thrombosis. If such a waveform is identified, further investigation is warranted.