Imaging description

May–Thurner syndrome, also known as iliac vein compression syndrome, or Crockett syndrome, is symptomatic compression of the left common iliac vein between the right common iliac artery and the lumbar vertebrae. Axial CT images will show that the right common iliac artery compresses the left common iliac vein (Figures 97.1 and 97.2). Patients with May–Thurner syndrome have an asymmetrically small left common iliac vein, which measured an average of 3.5mm in diameter in a study of 10 patients by Oguzkurt et al., which was significantly smaller than that in control subjects (11.5mm). The abnormality can be confirmed by iliac venography obtained via femoral access, which will demonstrate compression of the left common iliac vein in association with a pressure gradient (Figure 97.1). Patients with May–Thurner syndrome have a higher risk for acute or chronic deep venous thrombosis of the left-sided lower extremity (Figure 97.1). In patients with May–Thurner syndrome with chronic left common iliac venous occlusion, tortuous pelvic venous collaterals, which may connect to the contralateral veins, may be seen (Figure 97.2).

Importance

May–Thurner syndrome is important to recognize in patients with persistent left leg edema because relief of the mechanical compression of the left common iliac vein can prevent the development of deep venous thrombosis and venous insufficiency. Endovascular treatment with angioplasty and stent placement has been shown to be a safe and effective means of treating May–Thurner syndrome.

Typical clinical scenario

Patients with May–Thurner syndrome may present with acute or chronic left leg edema, limb pain, venous claudication, varicosities, deep venous thrombosis, chronic venous stasis, ulcers, phlegmasia cerulea dolens, or pulmonary embolism. This condition has been estimated to occur in 2% to 5% of patients who undergo evaluation for lower extremity venous disorders. It occurs predominantly in young to middle-aged women.

Contrast-enhanced CT or MRI typically shows external compression of the left common iliac vein caused by the right common iliac artery.