A Duplex Ultrasound Observational Study Establishing the Impact of Position on Left Iliac Vein Compression

Objective: The haemodynamics of non-thrombotic iliac vein lesions are not well understood. While stenosis may change with position, diagnostic testing is commonly conducted in supine. This study aimed to evaluate the impact of position on iliac vein stenosis. Methods: This was an observational cross sectional study, including women aged 16 years and older presenting with symptoms and signs of pelvic venous disease (n = 100). Patients were selected to have > 50% left common iliac vein diameter stenosis while supine. Data were collected on demographics, Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classes, and body mass indices (BMI). Duplex ultrasound was conducted both supine and standing. A stenosis of > 50% diameter reduction was determined by peak vein velocity ratio > 2.5, reverse flow of ipsilateral internal iliac vein (IIV), collaterals, or planimetric measurements. Results: The 100 women were characterised as young (38 ± 12.4 years) and lean (23.8 ± 5.2 kg/m2). As chosen, all patients had a > 50% iliac vein diameter stenosis while supine, but only 32 did on standing. Furthermore, reverse flow was noted in the ipsilateral IIV in 83 patients while supine, but in only 32 on standing. There was no difference in any signs and symptoms between the fixed and positional stenoses groups. Conclusion: This study revealed a high prevalence of position dependent iliac vein stenosis in two of three patients. Given that diagnostic testing is routinely conducted in supine, and patients experience symptoms during activity, this warrants modification of testing protocols. This study could help guide decisions for stent treatment and reduce overtreatment.