HL7 DG1 Segment: Diagnosis

The DG1 segment carries a single diagnosis assigned to the patient: the coded diagnosis, a free-text description, when it was diagnosed, its type (admitting, working, final), its priority, and the clinician who made it. A message may contain several DG1 segments — one per diagnosis — distinguished by the DG1-1 Set ID. Where PV1 says where the patient is, DG1 says what they have.

Purpose

DG1 communicates diagnostic findings for billing, clinical, and case-mix purposes. Each segment names one diagnosis with its coding method (ICD-9, ICD-10, etc.), the code itself, an optional description, the diagnosis date/time, and a required diagnosis type that separates an admitting diagnosis from a working or final one. DRG-related fields (DG1-7 through DG1-14, DG1-23 through DG1-25) support reimbursement grouping. Multiple diagnoses are sent as repeated DG1 segments, not a repeating field.

Used in

DG1 appears wherever a diagnosis is exchanged: ADT (admit/update events that carry diagnoses), ORU (results that report a diagnosis), DFT (financial transactions needing a diagnosis for charges), and BAR (billing/account messages). See ADT.

Field-by-field reference

Source: the Vorro HL7 segment database (extracted from the official v2-to-FHIR IG). R = required (cardinality min ≥ 1). Repeat = field may repeat. Length is not carried by the FHIR source and is shown as —.

Seq	Name	Data Type	Length	Req	Repeat	Table #	Description
DG1-1	Set ID	SI	—	R	—	—	Sequence number distinguishing repeated DG1 segments.
DG1-2	Diagnosis Coding Method	ID	—	R	—	—	Code system used, e.g. ICD-9, ICD-10.
DG1-3	Diagnosis Code	CWE	—	R	—	—	The coded diagnosis. The core field of the segment.
DG1-4	Diagnosis Description	ST	—	O	—	—	Free-text description of the diagnosis.
DG1-5	Diagnosis Date/Time	DTM	—	O	—	—	When the diagnosis was made.
DG1-6	Diagnosis Type	CWE	—	R	—	HL70052	Admitting, working, or final diagnosis.
DG1-7	Major Diagnostic Category	CE	—	O	—	—	DRG major diagnostic category.
DG1-8	Diagnostic Related Group	CE	—	O	—	—	Assigned DRG for the diagnosis.
DG1-9	DRG Approval Indicator	ID	—	O	—	—	Whether the DRG was approved.
DG1-10	DRG Grouper Review Code	IS	—	O	—	—	Outcome of grouper review.
DG1-11	Outlier Type	CE	—	O	—	—	Type of cost/length outlier.
DG1-12	Outlier Days	NM	—	O	—	—	Number of outlier days.
DG1-13	Outlier Cost	CP	—	O	—	—	Outlier cost amount.
DG1-14	Grouper Version And Type	ST	—	O	—	—	Version/type of the DRG grouper.
DG1-15	Diagnosis Priority	NM	—	O	—	HL70358	Rank of the diagnosis; `1` is primary.
DG1-16	Diagnosing Clinician	XCN	—	O	Y	—	Clinician(s) who made the diagnosis.
DG1-17	Diagnosis Classification	CWE	—	O	—	HL70228	Classification, e.g. diagnosis, complaint.
DG1-18	Confidential Indicator	ID	—	O	—	—	Whether the diagnosis is confidential.
DG1-19	Attestation Date/Time	DTM	—	O	—	—	When the diagnosis was attested/recorded.
DG1-20	Diagnosis Identifier	EI	—	O	—	—	Unique identifier for this diagnosis.
DG1-21	Diagnosis Action Code	ID	—	O	—	—	Add, update, delete action for the diagnosis.
DG1-22	Parent Diagnosis	EI	—	O	—	—	Identifier of a related parent diagnosis.
DG1-23	DRG CCL Value Code	CWE	—	O	—	HL70728	Complication/comorbidity level value.
DG1-24	DRG Grouping Usage	ID	—	O	—	—	Whether used in DRG grouping.
DG1-25	DRG Diagnosis Determination Status	CWE	—	O	—	HL70731	Status of the DRG diagnosis determination.
DG1-26	Present On Admission (POA) Indicator	CWE	—	O	—	HL70895	Whether condition was present on admission.

Most-used fields

DG1-3 Diagnosis Code is the core of the segment — the coded condition (typically ICD-10) that everything downstream keys on.
DG1-2 Diagnosis Coding Method names the code system, so a receiver knows how to interpret DG1-3.
DG1-6 Diagnosis Type is required and separates admitting from working from final diagnoses, driving how the diagnosis is used.
DG1-15 Diagnosis Priority ranks diagnoses; 1 marks the primary/principal diagnosis for billing and DRG grouping.
DG1-16 Diagnosing Clinician attributes the diagnosis to a provider and repeats when several clinicians concur.

Version differences (2.3 to 2.8.2)

2.3/2.4: DG1-16 through DG1-21 (diagnosing clinician, classification, confidential indicator, attestation date, identifier, action code) added; older versions stopped near DG1-15.
2.5: DG1-22 Parent Diagnosis added; coded fields move from CE toward CWE.
2.6/2.7+: DRG fields DG1-23 through DG1-25 and DG1-26 Present On Admission (POA) Indicator added.
DG1-4 Diagnosis Description and DG1-5 Diagnosis Date/Time have been deprecated in newer versions in favor of carrying detail through DG1-3 and the related DRG segment; receivers built for 2.3 ignore trailing fields they do not recognize.

Common mistakes

Trying to pack several diagnoses into one DG1 with a repeating code instead of sending one DG1 per diagnosis with incrementing Set IDs.
Omitting DG1-2 Diagnosis Coding Method, so the receiver cannot tell ICD-9 from ICD-10.
Treating DG1-6 Diagnosis Type as optional — it is required and downstream logic branches on it.
Ignoring DG1-15 Diagnosis Priority and losing which diagnosis is primary for DRG/billing.
Reading only the first repetition of DG1-16 when several diagnosing clinicians are listed.

Examples

Minimal valid DG1 (required fields only — Set ID, coding method, code, type):

DG1|1|I10|E11.9^Type 2 diabetes mellitus without complications^I10|||W

Fully-populated DG1:

DG1|1|I10|E11.9^Type 2 diabetes mellitus without complications^I10|Type 2 diabetes mellitus without complications|20260609103000|F||||||||||1|1234^SMITH^JANE^A^^^MD|D||20260609110000|DX0001||A||||Y|Y

Annotated breakdown of the fully-populated example (selected fields):

DG1                                          ← segment ID
1                                            ← DG1-1  Set ID
I10                                          ← DG1-2  Diagnosis Coding Method (ICD-10-CM)
E11.9^Type 2 diabetes...^I10                 ← DG1-3  Diagnosis Code
Type 2 diabetes mellitus...                  ← DG1-4  Diagnosis Description
20260609103000                               ← DG1-5  Diagnosis Date/Time
F                                            ← DG1-6  Diagnosis Type (Final)
1                                            ← DG1-15 Diagnosis Priority (primary)
1234^SMITH^JANE^A^^^MD                       ← DG1-16 Diagnosing Clinician
20260609110000                               ← DG1-19 Attestation Date/Time
DX0001                                       ← DG1-20 Diagnosis Identifier
A                                            ← DG1-21 Diagnosis Action Code (Add)
Y                                            ← DG1-26 Present On Admission Indicator

In-context inside an ADT^A01 (admit with admitting and working diagnoses):

MSH|^~&|REG|MERCYGEN|EHR|MERCYGEN|20260609120000||ADT^A01^ADT_A01|MSG001|P|2.5.1
EVN|A01|20260609120000
PID|1||MR12345^^^MERCYGEN^MR||DOE^JOHN^Q||19800101|M
PV1|1|I|3WEST^301^A||||1234^SMITH^JANE^A^^^MD|||MED||||ADM|||||V0001|||||||||||||||||||||||20260609120000
DG1|1|I10|J18.9^Pneumonia, unspecified organism^I10|||A
DG1|2|I10|J96.00^Acute respiratory failure^I10|||W

In-context inside a DFT^P03 (post detail financial transaction with the billing diagnosis):

MSH|^~&|BILL|MERCYGEN|FIN|MERCYGEN|20260612090000||DFT^P03^DFT_P03|MSG210|P|2.5.1
EVN|P03|20260612090000
PID|1||MR12345^^^MERCYGEN^MR||DOE^JOHN^Q||19800101|M
PV1|1|I|3WEST^301^A||||1234^SMITH^JANE^A^^^MD|||MED|||||||||V0001
DG1|1|I10|J18.9^Pneumonia, unspecified organism^I10|||F||||||||||1
FT1|1|||20260612|20260612|CG|99213^Office visit^CPT|||1|||3WEST

FHIR mapping

Primary target resource: Condition. DG1 also contributes to Encounter.diagnosis and EpisodeOfCare.diagnosis, both of which reference a Condition. Official ConceptMaps: Condition, Encounter, EpisodeOfCare.

Key Condition mappings:

DG1 field	FHIR target (Condition)
DG1-3 Diagnosis Code	`Condition.code` (CodeableConcept)
DG1-4 Diagnosis Description	`Condition.code.text`
DG1-5 Diagnosis Date/Time	`Condition.onsetDateTime`
DG1-16 Diagnosing Clinician	`Condition.asserter` (Practitioner)
DG1-19 Attestation Date/Time	`Condition.recordedDate` + asserted-date extension
DG1-20 Diagnosis Identifier	`Condition.identifier`
DG1-21 Diagnosis Action Code	`Condition.verificationStatus` (`entered-in-error`)
DG1-22 Parent Diagnosis	`Condition` extension `condition-dueTo` (Reference)

When mapped through Encounter or EpisodeOfCare, the same code/date/asserter values land on the referenced Condition, and two extra fields are used: DG1-6 Diagnosis Type → diagnosis.use (Encounter) / diagnosis.role (EpisodeOfCare) via the DiagnosisType vocabulary map, and DG1-15 Diagnosis Priority → diagnosis.rank.

Unmapped fields: the DRG/case-mix fields (DG1-2 coding method, DG1-7 through DG1-14, DG1-17 classification, DG1-18 confidential indicator, DG1-23 through DG1-26) have no published target in the DG1 ConceptMaps and are reimbursement/administrative details not represented on Condition.

Engine considerations

Required in practice: DG1-1 Set ID, DG1-2 coding method, DG1-3 code, and DG1-6 type. Real interfaces also expect DG1-15 priority for billing.
Iterate over all DG1 segments in a message and order them by DG1-1 Set ID / DG1-15 priority rather than arrival order.
Carry DG1-2 alongside DG1-3 so the code system survives — never assume ICD-10.
Preserve the repeating DG1-16 Diagnosing Clinician as an array.
Honor DG1-21 Diagnosis Action Code: an action of delete maps to a Condition.verificationStatus of entered-in-error, not a hard delete.

How Vorro parses and produces DG1

Vorro reads each DG1 segment as a separate diagnosis, keying on DG1-3 and tagging it with the DG1-2 coding method so the code system is unambiguous downstream. DG1-6 type and DG1-15 priority are preserved to drive admitting/working/final handling and primary-diagnosis selection. On the FHIR side Vorro emits a Condition per DG1 (code, onset, asserter, recordedDate) and links it from Encounter.diagnosis with diagnosis.use/diagnosis.rank set per the official ConceptMap; DG1-21 delete actions are rendered as verificationStatus entered-in-error.

DRG — diagnosis-related group detail that complements DG1's DRG fields.
PR1 — procedures, the companion to diagnoses.
ADT messages — where DG1 carries admit and update diagnoses.

Sources

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