RUO (and LDT) is international conventional nomenclature used to designate in-vitro diagnostic tests that have yet to be approved by regulatory agencies (FDA, Health Canada, etc.) but are commonly used by major laboratories and assay manufacturers (2, 3). The test result reports of RUO / LDT designated tests are required to bear those designations so the clinician is aware that the test is not yet clinically approved. However, this designation is not an indication of the potential clinical value of the tests/results. The term “RUO” is used primarily by assay manufacturers to designate assays that are in the process of validation and certification. The term “research use only” can be misleading as these assays are not restricted to “research” studies and are often used in a clinical setting.
