NON-INVASIVE HemodynamicS of Non-Thrombotic Iliac Vein Lesions ARE DISTURBED IN PATIEnTS with A HiSTORY OF Deep Venous Thrombosis.

OBJECTIVE

Non thrombotic iliac vein lesions (NIVL) are thought to be associated with deep vein thrombosis (DVT), yet most individuals with NIVL never develop thrombotic complications. This study assessed whether ultrasound-derived hemodynamic measurements differ between NIVL patients with and without a history of DVT, and whether these hemodynamic measurements better discriminate DVT history than percent stenosis alone.

METHODS

We performed a retrospective case-control study of patients evaluated at a tertiary academic referral center between 2022 and 2025 who underwent pelvic venous duplex ultrasound imaging. Patients with left common iliac vein stenoses greater than 20 percent were included and categorized by history of left lower extremity DVT. Exclusion criteria included concurrent DVT or prior venous stenting. Ultrasound images were digitized to obtain vessel diameters and spectral Doppler velocities in the iliac veins. Mean velocity, peak velocity, flow rate, shear rate, and ipsilateral and contralateral ratios were calculated. Continuous variables were compared using Welch t tests, with statistical significance defined as p<0.05.

RESULTS

45 patients were included, comprising 9 with prior DVT and 36 without. Amongst all metrics, velocity-based metrics at the compressed left common iliac vein showed the strongest associations with a history of prior DVT, including ipsilateral velocity ratio (log2 fold change -1.539, p=0.007), peak velocity (log2 fold change -0.999, p=0.002), and mean velocity (log2 fold change -0.989, p=0.002). Differences in percent stenosis were statistically significant but less discriminative than velocity-based metrics (log2 fold change 0.363, p=0.033). Composite metrics such as flow rate and shear rate demonstrated weaker discrimination. Dimensionality reduction analysis revealed distinct clustering based on multivariate hemodynamic features between patients with and without a history of DVT.

CONCLUSIONS

Among patients with NIVL, decreased velocity through the left common iliac vein at the compression point was the strongest predictor of prior DVT whereas percent stenosis was less discriminative. This study suggests that ultrasound-derived hemodynamic assessment can potentially provide a functional framework for risk stratification in patients with NIVL, but further prospective studies are needed to validate its clinical utility.