Duplication of the superficial femoral vein: recognition with duplex ultrasonography.

Duplication of the superficial femoral vein (SFV) is a normal variant seen in 20% of contrast phlebograms. Failure to identify thrombus in one limb of a SFV may lead to inappropriate management and subsequent complications. Colour Doppler imaging (CDI) is now the imaging technique of choice in the diagnosis of a deep vein thrombosis (DVT). The purpose of this study was to identify the prevalence of duplication of the SFV at CDI and to compare this with the known prevalence at contrast phlebography. CDI was performed on 58 healthy volunteers (116 limbs examined). Duplication of the SFV was present in 29 examinations (25%). Ultrasonic measurement of the diameter of the SFV was performed in all patients. In the presence of duplication a significant reduction in the diameter of both limbs of the SFV was noted when compared with an unduplicated vessel. The prevalence of duplication of the SFV at CDI is comparable to that at contrast phlebography. Recognition of this variant may help reduce false negative CDI examinations.