To enable reflex orders and resulting observation it is important to relate the observation that was generated back to the observation that indicated the need of a reflex test (a test performed within policy criteria under the authorization of the original service request).

The proposal is to add the following backbone element as an STU element to Observation with the associated definitions:

• Observation.triggeredBy        0..*        Backbone Element - Identifies the observation(s) that triggered the performance of this observation.
  • reference                     1..1        Reference(Observation)
  • type                             1..1        code (reflex | repeat | re-run) required binding
    • Reflex – performance of one or more other tests depending on the results of the initial test.  This may include collection of additional specimen.  Comment: While a new ServiceRequest is not required to perform the additional test, where it is still needed (e.g., requesting another laboratory to perform the reflex test), the Observation.basedOn would reference the new ServiceRequest that requested the additional test to be performed as well as the original ServiceRequest to reflect the one that provided the authorization.
    • Repeat (per policy) – performance of the same test again with the same parameters/settings/solution
    • Re-run (per policy) – performance of the same test but with different parameters/settings/solution
  • reason                          0..1        string - Provides the reason why this observation was performed as a result of the observation(s) referenced.