US · guidance
CMS SOM App. C, Tag D5775
§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.
Interpretive Guidelines §493.1281(a)-(c)
The laboratory must have a system to monitor and evaluate all testing it performs.
Examples of materials that may be used to evaluate the same test performed by different
methodologies, at multiple locations, and/or on multiple instruments in the same
laboratory are proficiency testing samples, split samples or “blind” testing of materials
with known values.
A laboratory that performs the same test at multiple locations or on more than one
instrument must have written criteria for acceptable differences in test values (e.g.,
between different or identical models of an instrument from the same manufacturer,
between instruments from different manufacturers).
If the laboratory performs calibration verification as specified in §493.1255(b), it may use
the calibration verification to meet the requirements at §493.1281(a), provided the 3
levels of materials used for calibration verification meet the laboratory’s criteria for
acceptable differences in test values.
History
Rev. 233; Issued: 09-12-25; Effective: 09-12-25; Implementation: 09-12-25
Provenance
- Source
- cms.gov
- Retrieved
- 2026-07-22
- Edition
- som-2026-07-22
- Content hash
cb5306cd6987d8f18f43f14a12b9eca1a1272971081835358731c80937e09ac0
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