Dimensional disparity between duplex and intravascular ultrasound in the assessment of iliac vein stenosis.

Minimum iliac vein caliber necessary to maintain normal peripheral venous pressure can be derived by the Poiseuille equation. Duplex was compared to intravascular ultrasound (IVUS) in the assessment of iliac vein stenosis in this single center retrospective study. Parallel IVUS and duplex caliber data for common iliac vein (CIV) and external iliac vein (EIV) in 382 limbs were separately compared. One or both segments were stenotic by IVUS criteria in 213 limbs. Neither segment was stenotic by IVUS in 22 limbs. Bland-Altman analyses and Passing-Bablok linear regressions were used. Duplex calibers were dimensionally than corresponding IVUS images of CIV and EIV segments in Bland-Altman comparison by a mean of 54 mm and 34 mm, respectively. Passing-Bablok regression suggested the difference was due to a systematic bias and not proportional. Duplex yields a smaller cross-sectional image of CIV and EIV compared to IVUS. Duplex is not a reliable diagnostic test for iliac vein stenosis.