Additional scenarios exist where AAP is also an acceptable alternative to fulfill compliance requirements, including:
Oversubscribed commercial PT
When PT is not available due to all approved PT programs being oversubscribed, the laboratory will not be penalized by regulatory agencies for using an AAP (eg, external split sample testing). Minimally, the frequency of assessment for the affected analytes must be biannual. When commercial PT becomes available, the analyte must be assessed with a commercial PT as required for compliance.
When a laboratory performs testing with more than one nonwaived test method, approved commercial PT is required on the primary test method only. However, when multiple testing methods are employed for a single analyte, testing performed on the same or different instrument makes/models or by alternate methods must be assessed against each other a minimum of twice per year (biannually). This assessment verifies comparability of results achieved by two different test methods/instruments.
Commercial PT not available
PT may not be available for specific circumstances to include, but not limited to:
- Unstable material/analyte (osmotic fragility)
- Analytes in unusual matrices (some body fluids, stool, etc.)
- In vivo testing (bleeding time)
Complex molecular and sequencing-based tests
For complex molecular testing including fluorescent in situ hybridization (FISH) and microarray and multiplex polymerase chain reaction (PCR)-based tests, AAPs may be performed by method or specimen type. For compliance, it is not required to test each analyte or abnormality.
In specific circumstances without commercial PT providers the testing must be assessed by an appropriate method minimally twice per year (biannually).