Section 493.1281 - Standard: Comparison of test results(a) If a laboratory performs the same test using different methodologies or instruments, or performs the same test at multiple testing sites, the laboratory must have a system that twice a year evaluates and defines the relationship between test results using the different methodologies, instruments, or testing sites.(b) The laboratory must have a system to identify and assess patient test results that appear inconsistent with the following relevant criteria, when available: (3) Diagnosis or pertinent clinical data.(4) Distribution of patient test results.(5) Relationship with other test parameters.(c) The laboratory must document all test result comparison activities.