Additional scenarios exist where AAP is also an acceptable alternative to fulfill compliance requirements, including:
Oversubscribed commercial PT
When PT is unavailable due to oversubscribed approved PT programs, regulatory agencies will not penalize the laboratory for using an AAP (e.g., external split sample testing). The frequency of assessment for the affected analytes must be at least biannual. When commercial PT becomes available, the analyte must be assessed with a commercial PT as required for compliance.
Multiple methods
Approved commercial PT is required only on the primary test method when laboratory tests have more than one nonwaived test method. 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 (bi-annually). This assessment verifies the comparability of results achieved by two test methods/instruments.
Commercial PT is 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), microarray, and multiplex polymerase chain reaction (PCR)-based tests, AAPs may be performed by method or specimen type. For compliance, each analyte or abnormality does not require testing.
In specific circumstances, without commercial PT providers, the testing must be assessed by an appropriate method minimally twice per year (bi-annually).
