Laboratory Service — Domain Model

Status: populated Owner: TBD Last updated: 2026-04-18 Companion: Service Template · 03 platform-services · 02 DDD

1. Aggregates

The root aggregate for a single laboratory work order. Groups specimens and results under one accession number.

Invariant	Rule
Unique accession number	Generated at creation; `{tenantShortCode}-{YYYYMMDD}-{seq6}` format
Cannot release without verification	At least one result must be in `verified` status before release
Cancellation preserves history	Status → `canceled`; sub-entities retain full audit chain
Critical ack required	Any result with `criticalFlag=true` must have a recorded acknowledgment before chart release

State machine:

A single analyte result within an Accession. Owned by the Accession aggregate.

Invariant	Rule
Immutable once released	Any change creates a new version; prior version status = `superseded`
Critical flag enforcement	Value crossing threshold sets `criticalFlag=true`; requires ack before release
Unit/code required	`testCode` + `unit` mandatory for numeric results
Correction chain	Each correction references `priorResultId` and supplies `correctionReason`

State machine:

Clinician acknowledgment of a released result. Lives in the results sub-domain.

Invariant	Rule
One ack per clinician per result version	Idempotent on duplicate submission
Ack types	`reviewed`, `forwarded`, `plan-documented`, `patient-notified`
Escalation trigger	Critical unacked results escalate after configurable timeout per site policy

Entity	Key attributes	Aggregate
`Specimen`	`id`, `accessionId`, `type`, `status`, `collectedAt`, `receivedAt`, `collectorId`, `condition`	Accession
`TestCatalogItem`	`id`, `name`, `loincCode?`, `specimenType`, `panel?`, `components[]`, `referenceRanges[]`, `tenantId?`	Catalog (independent)
`CriticalValuePolicy`	`id`, `testCode`, `lowCritical?`, `highCritical?`, `facilityId?`, `tenantId`	Config (independent)

Value Object	Fields	Rules
`AccessionNumber`	`value: string`	Unique per tenant per day
`ResultValue`	`quantity?: number`, `unit?: string`, `text?: string`, `boolean?: boolean`	One of quantity/text/boolean required
`ReferenceRange`	`low?`, `high?`, `unit?`, `ageRange?`, `sex?`, `text?`	At least one bound or text
`AbnormalFlag`	enum `N \| L \| H \| LL \| HH \| A \| AA`	Maps to FHIR `ObservationInterpretation`
`SpecimenCondition`	enum `satisfactory \| unsatisfactory \| hemolyzed \| lipemic \| clotted`	Drives processing path
`LabPriority`	enum `routine \| urgent \| stat`	Drives worklist sort order

Event name	Trigger	Key payload fields
`LabAccessionCreated`	Accession opened	`accessionId`, `patientId`, `orderId?`, `priority`, `tenantId`
`LabSpecimenCollected`	Collection recorded	`accessionId`, `specimenId`, `collectedAt`, `collectorId`, `tenantId`
`LabSpecimenReceived`	Lab receipt confirmed	`accessionId`, `specimenId`, `receivedAt`, `tenantId`
`LabResultEntered`	Value entered	`accessionId`, `resultId`, `testCode`, `tenantId`
`LabResultVerified`	Tech verified	`accessionId`, `resultId`, `verifiedBy`, `tenantId`
`LabResultReleased`	Released to chart	`accessionId`, `resultId`, `patientId`, `fhirObservationId`, `tenantId`
`LabCriticalValueTriggered`	Critical threshold crossed	`accessionId`, `resultId`, `patientId`, `testCode`, `value`, `tenantId`
`LabResultAcknowledged`	Clinician ack	`resultId`, `ackType`, `ackBy`, `tenantId`
`LabResultCorrected`	Correction applied	`resultId`, `priorResultId`, `correctionReason`, `tenantId`
`LabAccessionCanceled`	Accession canceled	`accessionId`, `reason`, `tenantId`

Term	Definition
Accession	A laboratory work order grouping specimens and tests for one patient visit
Accession number	Unique ID printed on specimen labels; traceable from collection through release
Bench	Physical or logical grouping of analyzers/technologists (Chemistry, Hematology, etc.)
Critical value	A result outside a threshold indicating immediate patient risk; requires urgent notification
Panel	A set of related tests ordered and reported together
Reference range	Expected value interval for an analyte, potentially age/sex/location adjusted
TAT	Turnaround time — interval from accession creation to result release
Verification	Technologist review and sign-off making a result eligible for release
Release	Making verified results available to the clinical chart
Correction	Revision to a verified/released result creating a new version
Worklist	Prioritized queue of pending tests for a bench or technologist
LOINC	Logical Observation Identifiers Names and Codes — standard lab test coding
UCUM	Unified Code for Units of Measure