Specimen Definition
A specimen definition is a facility's reusable rulebook for one kind of sample — what material to collect, how to prepare the patient, how to collect it, and how it must be contained and handled for testing. It exists so that the same expectations apply every time that sample type is ordered, no matter who draws it.
What it represents
In Care's FHIR-aligned model, a specimen definition maps to the SpecimenDefinition resource. It captures:
- What to collect — the material (blood, urine, swab, tissue), and whether a substitute is a
preferredoralternatechoice - Patient preparation — steps the patient follows beforehand, such as fasting
- How to collect — the collection procedure, from finger-prick to biopsy to clean-catch urine
- Containment and handling — the container, minimum volume, cap, temperature, and how long the sample stays usable
The key distinction is that a definition is a template, never an actual sample. It says how a kind of specimen should be handled; the physical tube drawn from a real patient is a Specimen. When a sample is drawn from a definition, it copies the definition's details into its own record — so the expectations are frozen at the moment of collection and can't be rewritten later.
A definition describes one container
Care keeps each definition deliberately narrow: it covers a single sample type held in a single container, including that container's capacity, minimum usable volume, cap, and any pre-treatment, plus the handling rules that keep the sample viable — temperature (room, refrigerated, or frozen), how long it can be held, and any special delivery instructions.
When a test genuinely needs several containers, you don't stretch one definition to cover them all. Instead, an Activity Definition composes the order from multiple definitions. This keeps each definition a clean, reusable unit rather than a bespoke recipe for one test.
Lifecycle
A definition is authored, published, and eventually withdrawn — never quietly edited once in use.
draft → active → retired
- draft — being authored, not yet referenced by orders
- active — published and available to orders
- retired — withdrawn from use; records that already used it stay intact
When the rules for a sample type change, Care bumps the definition's version instead of mutating the published record. Orders placed earlier stay faithful to what was actually expected at the time, which matters when a result is questioned months later.
How it connects
A specimen definition lives in the lab's catalogue and is pointed to — it is never attached to a patient:
- An Activity Definition or Service Request references it, so an order inherits its collection and handling rules
- A Specimen is instantiated from it when a real sample is drawn, preserving the link and a snapshot of the type
- That sample then flows into the Diagnostic Report once tested
Because catalogues are facility-scoped, each facility curates its own set of specimen kinds, each identified by a short, URL-safe slug that is unique within that facility.
Permissions
Access to specimen definitions is governed by facility-level permissions.
| Permission | Description | System Roles |
|---|---|---|
can_write_specimen_definition | Create and update specimen definitions in a facility's catalogue | Facility Admin, Admin |
can_read_specimen_definition | View specimen definitions when listing, ordering, collecting, or reviewing samples | Facility Admin, Administrator, Admin, Staff, Doctor, Nurse, Volunteer, Pharmacist |
Roles are granted through facility and organization memberships and cascade down the organization tree, so authoring stays with facility administrators while the wider clinical and lab team can read definitions to act on orders.
Related
- Reference: Specimen Definition (technical)
- Concept: Specimen
- Concept: Service Request
- Concept: Activity Definition
- Concept: Diagnostic Report