Comment:

The same comment you made about body site, and method applies here (10.1.7 Observation.bodySite - Only used if not implicit in code found in Observation.code. In many systems, this may be represented as a related observation instead of an inline component. If the use case requires BodySite to be handled as a separate resource (e.g. to identify and track separately) then use "The standard extension body-site-instance"). Should not have to specify if the specimen is implied by the test name.

Summary:

BodySite