This page is part of the HL7 Europe Laboratory Report (v0.1.0-ballot: STU 1 Ballot 1) based on FHIR R4. This is the current published version in its permanent home (it will always be available at this URL). For a full list of available versions, see the Directory of published versions

Design choices

Design Choices

Laboratory Report as HL7 FHIR document

There are two ways that could be considered for representing a Laboratory report in HL7 FHIR:

• by using the DiagnosticReport resource; or
• by treating the report as any other clinical document, i.e. theusing a HL7 FHIR document Bundle.

Considering that in many European countries:

• A Laboratory Report is a legally signed document
• Reports are often structured and may include different kinds of test results
• Several implementations are currently based on HL7 CDA (mainly IHE XD-LAB) and still use document exchange infrastructures (e.g. IHE XD*).

The team agreed to adopt the document representation for the Laboratory Report. This in fact:

• preserve the existing document-based paradigm, enabling for the REST one
• help the transition from the CDA-based solutions, by facilitating the reuse of the existing exchange infrastructures and of the on-development mapping artifacts used for the CDA to FHIR transformation

Support for DiagnoticReport

The team however recognized that typical HL7 FHIR consumers may expect to get Laboratory Reports by searching per DiagnosticReport.

The team looked therefore for a solution balancing the two approaches (FHIR document and DiagnosticReport); taking into account the R5 DiagnosticReport design pattern where the DiagnosticReport Vs Composition relationship is directed from the DiagnosticReport to the Composition resource.

The team agreed then that the Document Bundle representing the Laboratory Report shall always also include a DiagnosticReport resource.

This choice requires additional work to the creator, requesting to have some information consistently recorded in both DiagnosticReport and Composition, but it enables for more options for the consumer.

The following figure graphically summarizes the described design approach

Figure 1 - Overview of the report structure

Pre-adoption of R5 rules for Document bundles

To support the described approach, this guide pre-adopt the R5 rules for the inclusion of the resources in a document Bundle:

“The document bundle SHALL include only: <..> The supporting information: Any resources that are part of the graph of resources that reference or are referenced from the composition set, either directly or indirectly (e.g. recursively in a chain)”

in opposition to the R4 rules requiring that, with the exception of the Provenance resource and the Binary including the stylesheet, only resources directly or indirectly - referred from the composition can be included.

This choice has been made considering that:

• There was a good consensus in the HL7 FHIR community and in this team that the new rules are the most appropriate for a document bundle.
• In R5 the link between the DiagnosticReport and the Composition is realized with a Reference from the DiagnosticReport. The team decided to follow the same design pattern to facilitate the R4 to R5 transition.
• Adding a reference from the Composition to the DiagnosticReport would create an unwished circular reference.