Nonthrombotic iliac vein lesions (NIVLs), also referred to as a May-Thurner lesion/anatomy or Cockett syndrome, most frequently result from the left common iliac vein being compressed between the right common iliac artery and the spine. Iliac vein compression is often clinically silent, but can be associated with significant symptoms in which case it is referred to as May-Thurner syndrome. It is still unclear why some patients are asymptomatic whereas others can develop severe, debilitating symp…