The prevalence of asymptomatic left iliac vein compression in a cohort of Chinese patients

Abstract

Objective: Compression of the left common iliac vein (LCIV) between the overriding right common iliac artery and the lumbar vertebrae is an anatomic variant that may increase the risk of deep vein thrombosis. This study was to investigate the prevalence and risk factors of asymptomatic LCIV compression in a cohort of Chinese population. Methods: This was a retrospective analysis of patients undergoing abdominal contrast computer tomography (CT) scan for non-vascular disease from August 2018 to August 2019 at a single medical center. The diameter of iliac vein was measured from anterior to posterior venous wall on cross-section in the CT venous phase. The degree of LCIV compression was calculated as the diameter of LCIV at the site of maximal compression divided by the mean diameter of the uncompressed proximal and distal LCIV. A luminal reduction of ≥50% was defined as LCIV stenosis. Comparison of the variables between the stenotic and non-stenotic groups was performed, including gender, age, and body mass index (BMI). Result: A total of 692 patients were enrolled in this study including 351 males (51%) with a mean age of (38.8 ± 10.9) years old (range 18 to 71), and mean BMI of (22.8 ± 3.7) kg/m2. Fifty-six patients (56/692, 8.1%) had a past medical history of hypertension, 43 (6.2%) had diabetes mellitus, 23 (3.3%) had coronary arterial disease, and 80 patients (11.5%) were smokers. The mean diameters of LCIV at inferior vena cava junction, site of maximal compression, and uncompressed proximal and distal site were 15.5±3.2mm, 5.7±2.8mm, 9.9±2.4mm and 11.4±2.4mm.The mean rate of LCIV compression was 49%±18%. One hundred patients (100/692, 14%) had a LCIV compression of <25%, 248 patients (36%) had a compression of 25%-49%, 308 (45%) had a compression of 50%-74%, and 36 (5%) had a compression of ≥75%. Female gender (59% vs 39%, p<0.01), younger age (35.2±9.6 vs 42.3±10.9, p=0.001) and lower BMI (21.8±3.4 vs 23.7±3.7, p=0.045) were associated with the presence of LCIV stenosis. Conclusion: In this cohort of Chinese patients, radiological LCIV compression was common. LCIV stenosis was more likely to present in patients with female gender, younger age and lower BMI.