The importance of monophasic Doppler waveforms in the common femoral vein: a retrospective study.

OBJECTIVE: The purpose of this study was to assess the importance of monophasic waveforms encountered in the common femoral vein during deep venous thrombosis evaluation by a retrospective review of lower extremity venous Doppler (VD) sonography and correlative studies, such as computed tomography (CT) and magnetic resonance imaging. METHODS: A retrospective review was conducted of lower extremity VD studies performed from September 1, 2000, through September 1, 2005. All satisfactory VD studies, which were in compliance with the Intersocietal Commission for the Accreditation of Vascular Laboratories standard protocol, were evaluated for the presence of monophasic waveforms and correlated with CT of the abdomen and pelvis. Studies were evaluated for the causes of monophasic waveforms. Patients younger than 18 years were excluded. RESULTS: A total of 2963 VD examinations were reviewed. One hundred twenty-four of 2963 showed monophasic waveforms. Eighty-nine of the 124 had additional CT examinations within 1 week; 19 had CT within 2 months; and 16 had no additional examinations. Forty-seven of 124 cases revealed deep venous thrombosis extending into the iliac veins, of which 23 were identified by VD sonography; 26 were due to extrinsic compression; 6 showed a hypoplastic or stenosed common iliac vein; and the remaining 45 had no apparent causes for the monophasic waveforms. CONCLUSIONS: Monophasic waveforms in the common femoral veins are reliable indicators of proximal venous obstruction. Because iliac vein thrombosis is clinically important, we recommend routine sonographic evaluation of external iliac veins in the presence of monophasic waveforms and CT or magnetic resonance imaging, if necessary, to determine the cause of the monophasic waveforms.