Left common iliac vein compression in patients with May- Thurner syndrome: a 10-year retrospective study in an Australian cohort.

Abstract

Purpose: May-Thurner syndrome (MTS) is a clinical syndrome of left leg iliofemoral deep-venous thrombosis secondary to left common iliac vein (LCIV) compression. This study aimed to assess a diameter which constitutes clinically significant LCIV compression in patients with MTS. Material(s) and Method(s): IRB approval was obtained. 19 patients with MTS were retrospectively assessed over a 10-year period included by a diagnosis of MTS and the use of imaging with CT. Minimum LCIV diameter on CT was compared to 100 asymptomatic controls and 27 matched controls. Result(s): Mean LCIV diameter in MTS group was 3.82 mm (SD 1.38), control group (mean 7.17 mm SD 3.19, P < 0.0001), and matched control group (mean 6.86 mm SD 3.03, P = 0.007). A ROC curve was used to assess the diagnostic ability of a LCIV threshold. This showed in MTS patients, a LCIV diameter of <4.7mm had an 87.5% sensitivity and 72.7% specificity for diagnosis. Compression of the LCIV was also seen in asymptomatic controls with the minimum value in the matched control group 1.8 mm, and 22.2% had a minimum LCIV diameter less than the threshold value of 4.7mm. Conclusion(s): In patients with MTS, findings of LCIV compression on CT with a minimum diameter of <4.7 mm correlates with both high sensitivity and specificity for diagnosis. However, LCIV compression without symptoms does not constitute MTS, and placing clinical significance on such a finding when there are no symptoms should be exercised with caution as it may be a normal finding.