Prevalence of May-Thurner Syndrome in Patients with Deep Vein Thrombosis at a Large Medical Referral Center

Objective We set out to investigate the prevalence of May-Thurner syndrome (MTS) in a cohort of patients diagnosed with iliofemoral deep vein thrombosis at a large medical referral center. Materials and Methods We retrospectively analyzed a cohort of 496 patients who were referred to the emergency unit of a large medical referral center with suspected venous thromboembolism (VTE) and were diagnosed with deep vein thrombosis of the iliac veins and/or the thigh on ultrasound. We retrospectively assessed the presence of MTS in the primary ultrasound examination and on additional imaging (available in n = 193 patients). Results Across all 496 patients with iliofemoral deep vein thrombosis, the median age was 70 years. 238 patients (48 %) were female. The thrombosis was left-sided in 263 cases (53 %), right-sided in 208 cases ( 42 %) and bilateral in 24 cases (5 %). In the subgroup of patients with left-sided and bilateral thrombosis, the growth pattern was classified as ascending in 142 patients (50 %), descending in 104 patients (36 %) and unclear in 41 patients (14 %). Additional imaging tests were available in 193 patients: 119 patients (41 %) underwent CT, 18 patients (6 %) MRI and 30 patients (10 %) underwent phlebography. Within the subgroup of patients with left-sided and bilateral thrombosis, MTS was confirmed in 88 patients (31 %), and the imaging findings in 17 patients (6 %) were highly suspicious of MTS. Differentiation was not possible in 86 patients (30 %) and MTS was excluded in 96 patients (33 %). Conclusion Underlying MTS is not uncommon in the selected cohort of patients with deep iliofemoral vein thrombosis at a large referral center and should be excluded by imaging.