The left common iliac vein area

OBJECTIVE: To analyze the normal reference left common iliac vein (LCIV) area in chronic venous disease (CVD) patients with or without May–Thurner syndrome (MTS) and its relevant influencing factors. MATERIALS AND METHODS: A prospective analysis of patients with left lower extremity CVD was conducted in a single institution from January to August 2019. A total of 326 patients, 98 with MTS and 228 without MTS after computed tomography (CT) venography, were finally enrolled in this study, and their basic information was recorded. MTS cases were distinguished from non-MTS cases by calculating area stenosis rate with CT three-dimensional reconstruction. The reference area of LCIV was also defined and calculated to analyze its coefficient of variation and relationship with influencing factors in patients with and without MTS. RESULTS: Ninety-eight cases of MTS and 228 cases of non-MTS were finally analyzed. In the MTS group, the mean area of reference LCIV was significantly lower (116.29 ± 53.17 mm2 vs. 160.44 ± 52.99 mm2, P < 0.01) and showed greater variability (0.21 ± 0.13 vs. 0.16 ± 0.08, P = 0.04) compared with non-MTS group. Obesity radio was significantly higher in non-MTS group (28.5% vs. 16.3%, P = 0.03). In both MTS and non-MTS groups, the increase of body mass index (BMI) was generally associated with statistically significant increases in the LCIV area (P = 0.002 and P = 0.005), while other factors showed no statistically significant correlation. CONCLUSIONS: The reference area of LCIV was redefined in this study. We found that the increase of the LCIV area in both MTS and non-MTS groups was correlated with an increase in BMI. Furthermore, a smaller area of reference LCIV and more variability in the LCIV area were found in the MTS group in contrast to the non-MTS group.