Types of HL7 ADT message and an example of ADT^A04

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Iryna Mykhailova · Dec 8, 2022 11m read

#HL7 #HealthShare #InterSystems IRIS for Health

In the previous article, we've discussed the origin of the standard HL7v2, the structure and the types of messages. Let's now look at one of the most used types of messages and an example of its structure. I'm talking about ADT.

HL7 ADT messages (Admit, Discharge, Transfer) are used to communicate basic patient information, visit information and patient state at a healthcare facility. ADT messages are one of the most widely-used and high volume HL7 message types, as it provides information for many trigger events including patient admissions, registrations, cancellations, updates, discharges, patient data merges, etc.

All patient information is entered into a Hospital Information System (HIS) or Electronic Medical Record (EMR) in a healthcare setting. New patients or updates in these systems are distributed to ancillary systems through ADT messages to maintain the synchronization of current patient data.

There are quite a few subtypes of this message that depend on the situation and the action to be taken. Here are some of them.

Subtype	Description
ADT^A01	Patient admission/visit
ADT^A02	Patient transfer
ADT^A03	Patient discharge
ADT^A04	Patient registration
ADT^A05	Patient pre-admission
ADT^A08	Patient information update
ADT^A11	Cancel patient admission
ADT^A12	Cancel patient transfer
ADT^A13	Cancel patient discharge

If we look at the general structure of this type of message, it will consist of the following segments. Considering that different versions f the HL7v2 support backward compatibility, in higher versions you may have more fields.

Segments of HL7 ADT

Segment	Description
MSH	Message Header. Each message must contain a message header, known as an MSH segment within an ADT. The header contains information about the sending system and location, the receiving system and location, the date and time of when the message was created, the type of trigger event being communicated, and the HL7 message version being used.
EVN	Event Type. Communicates the event that occurred in order for the message to be generated. This segment is a crucial part of the data flow, as it indicates where and when a message is sent based on the type of event.
PID	Patient Identification. Important patient identification information, including patient demographics.
[{NK1}]	Next of Kin. Contact information of the patient’s closest living relative(s) in case they need to be contacted. This segment can be repeated as necessary.
PV1	Patient Visit. Information about a patient’s account or any visit-specific details, such as servicing facility, attending doctor, and visit ID are held in this segment.
[PV2]	Patient Visit - Additional Info. This segment is a continuation of information specific to the patient’s visit, and is the segment where the Admit Reason is communicated. It is an optional segment if a DG1 segment is included in the message. If there is no DG1 segment, then the PV2 segment is required.
[{OBX}]	Observation/Result. Each OBX segment carries information about a single medical observation or result. This segment is more frequently used in ORU (Observational Report) messages. It can be repeated as necessary.
[{AL1}]	Allergy Information. Contains information about a patient’s allergies including allergen type, reaction and severity. This segment can be repeated as necessary.
[{DG1}]	Diagnosis Information. This segment contains information about a patient’s diagnosis and uses ICD coding standards to communicate specific diseases, signs, symptoms, abnormalities, patient complaints, etc.
[{PR1}]	Procedures. Holds information about the various procedures that can be performed on a patient, and can be repeated to communicate information about multiple procedures.
[{ROL}]	Role. The personnel and event involvement information necessary to add, update, correct and delete from the patient record.
[{GT1}]	Guarantor Information. Information about a patient’s guarantor (i.e. the person financially responsible for the patient’s account) is held in this segment. This segment is particularly useful when communicating with insurance billing applications.
[{IN1..2..3}]	Insurance Information. The insurance policy coverage information, such as plan and provider identifiers, necessary to produce patient and insurance bills.

[ ] = optional segment, { } = repeating segment

Now that we know the building blocks of this type of messages, let's look at an example.

Example of HL7 ADT^A04 message

Let's say we have the following message:

MSH|^~\&|EPIC|EPICADT|SMS|SMSADT|202211031408|CHARRIS|ADT^A04|1817457|D|2.5|
EVN||202211030800||||202211030800
PID||0493575^^^2^ID 1|454721||DOE^JOHN^^^^|DOE^JOHN^^^^|19480203|M||B|254 MYSTREET AVE^^MYTOWN^OH^44123^USA||(216)123-4567|||M|NON|400003403~1129086|
NK1||ROE^MARIE^^^^|SPO||(216)123-4567||EC|||||||||||||||||||||||||||
PV1||O|168 ~219~C~PMA^^^^^^^^^||||277^ALLEN MYLASTNAME^BONNIE^^^^|||||||||| ||2688684|||||||||||||||||||||||||202211031408||||||002376853

In this example, you will notice that we have 5 distinct segments separated by the carriage return character: MSH, EVN, PID, NK1 and PV1.

You will also notice that each segment contains a number of composites. For example, in the first line, the pipe character (|) separates the SMS and SMS ADT segments.

Finally, on the second line, the first name sub-field JOHN is separated from the last name DOE using the ^ character.

Also, there is always an indicator of the version of the used HL7v2 standard so that the receiving application knows what to expect in which field. In this instance, the version is 2.5.

Now let's look at each segment of this message and learn what info it carries.

Segment MSH

	Field	Length	Optionality	Value
MSH.1	Field Separator	1	Required	\|
MSH.2	Encoding Characters	4	Required	^~\&
MSH.3	Sending Application	227	Optional	EPIC
MSH.4	Sending Facility	227	Optional	EPICADT
MSH.5	Receiving Application	227	Optional	SMS
MSH.6	Receiving Facility	227	Optional	SMSADT
MSH.7	Date/Time Of Message	26	Required	202211031408
MSH.8	Security	40	Optional	CHARRIS
MSH.9	Message Type	15	Required	ADT^A04
MSH.10	Message Control ID	20	Required	1817457
MSH.11	Processing ID	3	Required	D
MSH.12	Version ID	60	Required	2.5
MSH.13	Sequence Number	15	Optional
MSH.14	Continuation Pointer	180	Optional
MSH.15	Accept Acknowledgment Type	2	Optional
MSH.16	Application Acknowledgment Type	2	Optional
MSH.17	Country Code	3	Optional
MSH.18	Character Set	16	Optional
MSH.19	Principal Language Of Message	250	Optional
MSH.20	Alternate Character Set Handling Scheme	20	Optional
MSH.21	Message Profile Identifier	427	Optional

Segment EVN

	Field	Length	Optionality	Value
EVN.1	Event Type Code	3	Backward Compatibility
EVN.2	Recorded Date/Time	26	Required	202211030800
EVN.3	Date/Time Planned Event	26	Optional
EVN.4	Event Reason Code	3	Optional
EVN.5	Operator ID	250	Optional
EVN.6	Date/Time of Event	26	Optional	202211030800
EVN.7	Event Facility	241	Optional

Segment PID

PID||0493575^^^2^ID 1|454721||DOE^JOHN^^^^|DOE^JOHN^^^^|19480203|M||B|254 MYSTREET AVE^^MYTOWN^OH^44123^USA||(216)123-4567|||M|NON|400003403~1129086|

	Field	Length	Optionality	Value
PID.1	Set ID - PID	4	Optional
PID.2	Patient ID	20	Backward Compatibility	0493575^^^2^
PID.3	Patient Identifier List	250	Required	D 1
PID.4	Alternate Patient ID - PID	20	Backward Compatibility	454721
PID.5	Patient Name	250	Required	DOE^JOHN^^^^
PID.6	Mother's Maiden Name	250	Optional	DOE^JOHN^^^^
PID.7	Date/Time of Birth	26	Optional	19480203
PID.8	Administrative Sex	1	Optional	M
PID.9	Patient Alias	250	Backward Compatibility
PID.10	Race	250	Optional	B
PID.11	Patient Address	250	Optional	254 MYSTREET AVE^^MYTOWN^OH^44123^USA
PID.12	County Code	4	Backward Compatibility
PID.13	NPhone Number - Home	250	Optional	(216)123-4567
PID.14	Phone Number - Business	250	Optional
PID.15	Primary Language	250	Optional
PID.16	Marital Status	250	Optional	M
PID.17	Religion	250	Optional	NON
PID.18	Patient Account Number	250	Optional	400003403~1129086
PID.19	SSN Number - Patient	16	Backward Compatibility
PID.20	Driver's License Number - Patient	25	Backward Compatibility
PID.21	Mother's Identifier	250	Optional
PID.22	Ethnic Group	250	Optional
PID.23	Birth Place	250	Optional
PID.24	Multiple Birth Indicator	1	Optional
PID.25	Birth Order	2	Optional
PID.26	Citizenship	250	Optional
PID.27	Veterans Military Status	250	Optional
PID.28	Nationality	250	Backward Compatibility
PID.29	Patient Death Date and Time	26	Optional
PID.30	Patient Death Indicator	1	Optional
PID.31	Identity Unknown Indicator	1	Optional
PID.32	Identity Reliability Code	20	Optional
PID.33	Last Update Date/Time	26	Optional
PID.34	Last Update Facility	241	Optional
PID.35	Species Code	250	Conditional
PID.36	Breed Code	250	Conditional
PID.37	Strain	80	Optional
PID.38	Production Class Code	250	Optional
PID.39	Tribal Citizenship	250	Optional

Segment NK1

	Field	Length	Optionality	Value
NK1.1	Set ID - NK1	4	Required
NK1.2	NK Name	250	Optional	ROE^MARIE^^^^
NK1.3	Relationship	250	Optional	SPO
NK1.4	Address	250	Optional
NK1.5	Phone Number	250	Optional	(216)123-4567
NK1.6	Business Phone Number	250	Optional
NK1.7	Contact Role	250	Optional	EC
NK1.8	Start Date	8	Optional
NK1.9	End Date	8	Optional
NK1.10	Next of Kin / Associated Parties Job Title	60	Optional
NK1.11	Next of Kin / Associated Parties Job Code/Class	20	Optional
NK1.12	Next of Kin / Associated Parties Employee Number	250	Optional
NK1.13	Organization Name - NK1	250	Optional
NK1.14	Marital Status	250	Optional
NK1.15	Administrative Sex	1	Optional
NK1.16	Date/Time of Birth	26	Optional
NK1.17	Living Dependency	2	Optional
NK1.18	Ambulatory Status	2	Optional
NK1.19	Citizenship	250	Optional
NK1.20	Primary Language	250	Optional
NK1.21	Living Arrangement	2	Optional
NK1.22	Publicity Code	250	Optional
NK1.23	Protection Indicator	1	Optional
NK1.24	Student Indicator	2	Optional
NK1.25	Religion	250	Optional
NK1.26	Mother's Maiden Name	250	Optional
NK1.27	Nationality	250	Optional
NK1.28	Ethnic Group	250	Optional
NK1.29	Contact Reason	250	Optional
NK1.30	Contact Person's Name	250	Optional
NK1.31	Contact Person's Telephone Number	250	Optional
NK1.32	Contact Person's Address	250	Optional
NK1.33	Next of Kin/Associated Party's Identifiers	250	Optional
NK1.34	Job Status	2	Optional
NK1.35	Race	250	Optional
NK1.36	Handicap	2	Optional
NK1.37	Contact Person Social Security Number	16	Optional
NK1.38	Next of Kin Birth Place	250	Optional
NK1.39	VIP Indicator	2	Optional

Segment PV1

PV1||O|168 ~219~C~PMA^^^^^^^^^||||277^ALLEN MYLASTNAME^BONNIE^^^^|||||||||| ||2688684|||||||||||||||||||||||||202211031408||||||002376853

	Field	Length	Optionality	Value
PV1.1	Set ID - PV1	4	Optional
PV1.2	Patient Class	1	Required	O
PV1.3	Assigned Patient Location	80	Optional	168 ~219~C~PMA^^^^^^^^^
PV1.4	Admission Type	2	Optional
PV1.5	Preadmit Number	250	Optional
PV1.6	Prior Patient Location	80	Optional
PV1.7	Attending Doctor	250	Optional	277^ALLEN MYLASTNAME^BONNIE^^^^
PV1.8	Referring Doctor	250	Optional
PV1.9	Consulting Doctor	250	Rétrocompatibilité
PV1.10	Hospital Service	3	Optional
PV1.11	Temporary Location	80	Optional
PV1.12	Preadmit Test Indicator	2	Optional
PV1.13	Re-admission Indicator	2	Optional
PV1.14	Admit Source	6	Optional
PV1.15	Ambulatory Status	2	Optional
PV1.16	VIP Indicator	2	Optional
PV1.17	Admitting Doctor	250	Optional
PV1.18	Patient Type	2	Optional
PV1.19	Visit Number	250	Optional	2688684
PV1.20	Financial Class	50	Optional
PV1.21	Charge Price Indicator	2	Optional
PV1.22	Courtesy Code	2	Optional
PV1.23	Credit Rating	2	Optional
PV1.24	Contract Code	2	Optional
PV1.25	Contract Effective Date	8	Optional
PV1.26	Contract Amount	12	Optional
PV1.27	Contract Period	3	Optional
PV1.28	Interest Code	2	Optional
PV1.29	Transfer to Bad Debt Code	4	Optional
PV1.30	Transfer to Bad Debt Date	8	Optional
PV1.31	Bad Debt Agency Code	10	Optional
PV1.32	Bad Debt Transfer Amount	12	Optional
PV1.33	Bad Debt Recovery Amount	12	Optional
PV1.34	Delete Account Indicator	1	Optional
PV1.35	Delete Account Date	8	Optional
PV1.36	Discharge Disposition	3	Optional
PV1.37	Discharged to Location	47	Optional
PV1.38	Diet Type	250	Optional
PV1.39	Servicing Facility	2	Optional
PV1.40	Bed Status	1	Rétrocompatibilité
PV1.41	Account Status	2	Optional
PV1.42	Pending Location	80	Optional
PV1.43	Prior Temporary Location	80	Optional
PV1.44	Admit Date/Time	26	Optional	202211031408
PV1.45	Discharge Date/Time	26	Optional
PV1.46	Current Patient Balance	12	Optional
PV1.47	Total Charges	12	Optional
PV1.48	Total Adjustments	12	Optional
PV1.49	Total Payments	12	Optional	002376853
PV1.50	Alternate Visit ID	250	Optional
PV1.51	Visit Indicator	1	Optional
PV1.52	Other Healthcare Provider	250	Optional

This is it for now. Find out more about HL7v2 on the official portal.

Any comments/suggestions are welcome in the comments section.