IS Case 183: Duplication of femoral veins with single deep venous thrombosis
Imaging Sciences URMC 2008
Publication Date: 2009-05-21
Duplication of the right femoral veins with non-compressible, thin-walled grayscale appearance of one of the veins and absence of flow by color Doppler. Second femoral vein patent both by assessment of compressibility and color Doppler flow.
Deep venous thrombosis (DVT) is a common condition with significant associated morbidity and mortality, representing the primary cause of approximately 600,000 hospitalizations/year in the US alone and are found on autopsy in approximately 15% of hospital deaths. Compression ultrasonography is the initial diagnostic imaging modality of choice for the evaluation of both symptomatic DVT and screening of high-risk asymptomatic patients. Doppler US allows additional characterization of thrombus as occlusive vs. non-occlusive based on absence or presence of flow, respectively.
In symptomatic patients, sensitivity and specificity of compression US exceed 95% and 98% respectively in diagnosis of proximal lower extremity DVT relative to the gold-standard of lower extremity venography. Although not as effective in the evaluation of distal/calf vein DVT in symptomatic patients (11-100% sensitivity, 90-100% specificity), the prevalence of isolated calf DVT in symptomatic patients is less than 20%. Compression US is less useful in asymptomatic lower extremity DVT, which tend to be smaller, discontinuous, non-occlusive, and more geographically variable.
Acute and chronic DVT have distinct grayscale and Doppler features; acute thrombus ranges from anechoic to echoic with distension of otherwise normal-appearing vessel walls with limited to non-compressible lumen with absent flow by Doppler, while chronic thrombus tends to be echoic and partly compressible with thickened vessel walls of normal caliber with recanalized antegrade flow with or without reflux.
Duplication of the femoral vein is a common anatomic variant with as many as 40% of patients demonstrating some degree of duplication and represents an important cause of missed proximal femoral thromboses.
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