The purpose of our educational exhibit is to: Review May-Thurner syndrome (MTS) definition, clinical presentation, and classification. Illustrate the range of imaging techniques employed and their diagnostic correlates. Highlight diagnostic challenges.

Historical background and definition As early as 1851, Virchow noted a striking five-fold left-sided preponderance for lower extremity deep venous thrombosis (DVT). [1] It was not until the seminal cadaveric study by May and Thurner in 1957 that comprehensive description of the anatomy underlying this peculiarity was provided. [2] Namely, compression of the left common iliac vein (LCIV) by the overlying right common iliac artery (RCIA, Fig. 1,2). The authors postulated that venous 'spurs' arose through a combination of chronic mechanical compression and endothelial disruption...

A literature review has been performed. Both clinical and radiological characteristics of MTS will be presented, including a classification system. Clinical presentation Acutely, presentation includes, left lower extremity DVT in the absence of differential causes of iliofemoral thrombosis. Chronically, patients may note venous claudication, post thrombotic syndrome, and chronic venous insufficiency which often doesn't respond to conventional management. Positive clinical outcomes often rely on early diagnosis and treatment. However, this represents a challenge due to the significant proportion of patients with asymptomatic disease. Classification Stage...

May-Thurner syndrome can have profound consequences and is under-appreciated as a cause for DVT and chronic venous insufficiency. In contrast to normal variance, pathological MTS may be defined by persistent LCIV narrowing, regardless of patient positioning, with haemodynamic compromise. It is important to understand clinical manifestations, diagnostic options, and imaging limitations in this group of patients.

Maira Hameed BA (Hons) BM BCh Academic Section of Vascular Surgery, Division of Surgery, Department of Surgery & Cancer, Imperial College London, Charing Cross Hospital, London, UK Sarah Onida BSc MBBS MRCS Academic Section of Vascular Surgery, Division of Surgery, Department of Surgery & Cancer, Imperial College London, Charing Cross Hospital, London, UK Alun H DaviesMA DM DSC FRCS FHEA FEBVS FACPH Academic Section of Vascular Surgery, Division of Surgery, Department of Surgery & Cancer, Imperial College London, Charing Cross Hospital, London, UK

1.Virchow R. Ueber die Erweiterung kleinerer Gefäfse. Archiv f pathol Anat. 1851;3(3):427-462. 2.May R, Thurner J. The Cause of the Predominantly Sinistral Occurrence of Thrombosis of the Pelvic Veins. Angiology1957;8(5):419-427. 3.Liu Z, Gao N, Shen L, et al. Endovascular Treatment for Symptomatic Iliac Vein Compression Syndrome: A Prospective Consecutive Series of 48 Patients. Ann Vasc Surg 2014; 28: 695-704. 4.Mcdermott S, Oliveira G, Ergul E, et al. May-thurner syndrome: can it be diagnosed on a single magnetic resonance venography study? Diagn Interv Radiol 2013; 19:...