Prevalence and predictors of radiological left common iliac vein compression in asymptomatic patients

Abstract

Objective: The aim of this study was to investigate the prevalence of radiological left common iliac vein (LCIV) compression among the asymptomatic population and identify possible predictors.

Methods: Contrast-enhanced abdominal and/or pelvic computed tomography scans of eligible asymptomatic patients were examined. The LCIV diameter was measured from different horizontal planes in the venous phase using PACSView. Degree of LCIV compression (D_c) was calculated by a predefined formula and graded as insignificant (D_c < 25%), mild (≥25% D_c < 50%), moderate (≥50% D_c <75%), and severe (D_c ≥ 75%). Venous stenosis was defined as a D_c of ≥50%. Comparison of variables, including gender, age, body mass index (BMI), and comorbidities was performed between the different grades of LCIV compression.

Results: Between November 2019 and July 2022, 1698 eligible asymptomatic patients (53.1% females; mean age, 39.3 ± 11.8 years; mean BMI, 22.9 ± 3.6 kg/m²) were reviewed. The mean D_c was 46.2% (range, 0.29%-90.4%). Insignificant, mild, moderate, and severe compression were distributed in 14.5%, 38.0%, 42.2%, and 5.2% of the cohort population, respectively. Prevalence of venous stenosis was higher in females than males (58.1% vs 42.2%; χ² = 15.52; P < .001). Females aged ≥25 and <35 years accounted for the highest proportion of venous stenosis than other age groups and was a significant predictor (odds ratio [OR], 3.18; 95% confidence interval [CI], 1.74-7.79; P < .001). In the Asian BMI classification group, being underweight is associated with venous stenosis (OR, 4.69; 95% CI, 2.70-8.14; P < .001) and obesity may be a protective factor (OR, 0.38; 95% CI, 0.23-0.64; P < .001). There is an inverse relationship between D_c and age and BMI.

Conclusions: The prevalence of radiological LCIV compression on computed tomography scans was high, but all patients were asymptomatic. Female gender, especially those aged ≥25 and <35 years, and underweight were possible predictors for venous stenosis.

Keywords: Chronic venous insufficiency; Left common iliac vein compression; May-Thurner syndrome; Radiology; Venous thromboembolism.

Graphical abstract

Fig 1

Computed tomography (CT) images and illustration on acquiring measurement locations. (A) In the sagittal view, the narrowest diameter of the left common iliac vein (LCIV) owing to maximum compression by the right common iliac artery (RCIA) is marked (red arrow). (B) The point (∗) of compression in coronal view, which is processed to locate the other points as shown in (C) D₁ is acquired as the midpoint of L₁ (distance between confluence to inferior vena cava (IVC) and D₂); D₄ is at most 1.25 mm proximal to the confluence of LCIV; D₃ is the acquired as the midpoint of L₂ (distance between D₂ and D₄). The anteroposterior (AP) diameters of D₁ to D₄ are subsequently taken in axial view at the level of the respective points.

Fig 2

Examples of axial computed tomography (CT) measurement of the minimum anteroposterior (AP) diameters (distance between red arrows) of the left common iliac vein (LCIV) in an asymptomatic patient and a patient with May-Thurner syndrome (MTS).

Fig 3

Flowchart illustrating the screening and selection process of asymptomatic patients. CT, computed tomography.

Fig 4

Scatter plot matrix demonstrating the relationship between the degree of left common iliac vein (LCIV) compression and age and body mass index (BMI).