What makes a SNOMED CT PaLM reportable?

This section provides information about SNOMED CT Pathology and Laboratory Medicine (PaLM) concepts. 

A SNOMED CT PaLM reportable is a single data item in a pathology report identifying the specific lab test to which a value/interpretation can be assigned. SNOMED CT ‘Observable entity’ concepts are used, and it’s useful to think of these concepts as asking a question; in this example, ‘what is the result of the substance concentration of bicarbonate in urine test?’

Information about a lab test is carried inherently in a SNOMED CT PaLM reportable, with concepts carrying coded attributes relating to a test’s property, component, specimen, and where stated, technique. These elements are also seen in the human-readable description of a SNOMED CT PaLM reportable’s ‘fully specified name’. By establishing the equivalent lab source data, one can subsequently identify the correct target SNOMED CT PaLM reportable to map to - see Pre-processing source and target terminology.

There are currently around 3,900 SNOMED CT PaLM reportables covering: 

• biochemistry 
• haematology 
• immunology 
• microbiology – this includes bacteriology, virology and serology 
• transfusion medicine

To aid implementation, all SNOMED CT PaLM reportables are published in a SNOMED CT reference set (Refset):

1853551000000106 Pathology and Laboratory Medicine observable entity simple reference set (foundation metadata concept) 

Users can also browse SNOMED CT PaLM content using the search function in NHS England’s SNOMED CT Browser.

For labs who wish to integrate SNOMED CT PaLM directly into their information systems, the Refset is included in the SNOMED CT UK Clinical Edition; available via NHS England’s TRUD website, or via NHS England’s Terminology Server (detailed information on how to access SNOMED CT content is available via NHS England's Delen website).

However, most mapping tools enable this Refset to be accessed without the requirement to integrate SNOMED CT directly. Dependent on a tool’s functionality, constraining map targets to this Refset may require the user to enter the following Expression Constraint Language (ECL) expression:

^ 1853551000000106 |Pathology and Laboratory Medicine observable entity simple reference set (foundation metadata concept)| 

SNOMED CT PaLM reportables are all single reportables - that is, they each represent a single lab test result code. They do not represent panels/batteries, profiles, complex reports, or other such ‘groupers’. Instead, multiple SNOMED CT PaLM reportables would be contained in such grouped pathology reports. 

For example, a complex microbiology report such as a urinary microscopy, culture and sensitivities test report might contain several SNOMED CT PaLM reportables such as: 

• qualitative result of Staphylococcus aureus culture (observable entity)
• susceptibility of organism to flucloxacillin (observable entity)
• qualitative result of hyaline casts in mid-stream urine microscopy (observable entity)

How such SNOMED CT PaLM reportables can be identified as appropriate for use in grouped reports depends on the type of report. For panels and profiles, this is straightforward, as local single reportables are already identified in the report and can be mapped accordingly. For complex microbiology reports, a method by which appropriate SNOMED CT PaLM reportables can be identified is described in chapter 7 - Algorithmic mapping.

Other data elements in the Pathology FHIR Specification (those that supplement SNOMED CT PaLM reportables) can be populated with different types of SNOMED CT codes. For example, lab test result values such as Positive (qualifier value) or lab test specimen types such as Venous blood (substance). 

This supports the sharing of atomic, coded data in pathology reports.

The mapping process involved is described in Section 7 - Algorithmic mapping.

In addition to reportables, SNOMED CT PaLM also provides concepts that represent lab test request codes (‘requestables’). These are single data items in the report identifying the specific test(s) requested. SNOMED CT ‘Procedure’ concepts are used for this purpose.

To aid implementation, all SNOMED CT PaLM requestables are published in a SNOMED CT reference set (Refset):

1853561000000109 Pathology and Laboratory Medicine procedure simple reference set (foundation metadata concept)