Chylothoraces are encountered at a rate of up to 1 in 6,000 in all hospital admissions. The etiology of these chylothoraces can be categorized into traumatic or nontraumatic. Traumatic or iatrogenic chylothorax can be seen in up to half of all chylothoraces with nontraumatic or unknown etiology constituting the remaining majority. Treatment planning is essential in chylothorax due to the varying etiologies. Lymphangiography continues to be usually appropriate, as it is both an effective diagnostic and a therapeutic intervention. Additionally, with development in MR technology, MR lymphangiography has advanced rapidly in the last decade and is an additional radiological procedure that is usually appropriate in all etiologies of chylothoraces. Ultrasound is not appropriate for treatment planning in all etiologies and CT chest without contrast is not appropriate in nontraumatic etiologies of chylothoraces. All other radiological procedures may be appropriate based on individual cases. 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.
