CDA document structure
A CDA document is wrapped by the <ClinicalDocument>
element, and contains a header and a body. The
header lies between the <ClinicalDocument>
and the
<structuredBody>
elements. This identifies and
classifies the document and provides information on authentication, the encounter, the
patient, and the involved providers.
The body contains the clinical report. This is an unstructured blob or
contains structured markup. This example shows a structured body, which is wrapped by
the <structuredBody>
element, and which is divided
up into recursively nestable document sections.
A CDA document section is wrapped by the
<section>
element. Each section can contain a
single narrative block, and any number of CDA entries and external references.
The CDA narrative block is wrapped by the
<text>
element within the
<section>
element, and must contain the
human-readable content to be rendered.
Within a document section, the narrative block represents content to be rendered. CDA entries represent structured content provided for further computer processing. For example, decision support applications. CDA entries typically encode content present in the narrative block of the same section.
The example shows two
<observation>
CDA entries, and a
<substanceAdministration>
entry containing a
nested
<supply>
entry, although several other CDA entries
are defined.
CDA entries can nest and can reference external objects. CDA external
references always happen within the context of a CDA entry. External references refer to
content that exists outside this CDA document. For example, an image, procedure, or
observation that is wrapped by the <externalObservation>
element. Externally referenced material is not
covered by the authentication of the document referencing it.
Although the narrative blocks must always be present, the CDA entries are optional. An originator of a CDA document is not required to fully encode all narrative into CDA entries within the CDA body. A recipient is not required to parse and interpret the complete set of CDA entries contained within the CDA body.
Within an implementation, trading partners can ascribe additional originator and recipient responsibilities. These responsibilities create various entries and can create various templates or implementation guides that require the use of various entries.
Therefore, CDA can be implemented or relatively detailed to implement. This provides a migration pathway toward progressively richer computer-processable content.
Example:
<ClinicalDocument>
... CDA Header ...
<structuredBody>
<section>
<text>...</text>
<observation>...</observation>
<substanceAdministration>
<supply>...</supply>
</substanceAdministration>
<observation>
<externalObservation>...
</externalObservation>
</observation>
</section>
<section>
<section>...</section>
</section>
</structuredBody>
</ClinicalDocument>