ACR Appropriateness Criteria® Nonthrombotic Iliac Vein Lesion

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 symptoms. Most frequently, this disorder can cause lower extremity edema, deep venous thrombosis, or chronic venous insufficiency. Since NIVL can be clinically silent, a thorough history and physical examination is needed to rule out alternative etiologies. For symptomatic patients, imaging evaluation is warranted to make a definitive diagnosis. The objectives of imaging in a symptomatic patient include confirmation of diagnosis, identifying the location and extent of occlusion, and procedural planning. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.