HL7 IHE PAM Message Parser and Explainer

Overview

This skill parses and explains HL7 v2.5 IHE PAM (Patient Administration Management) messages - the standard healthcare interoperability format for patient administration events. The parser identifies message types, extracts segments and fields, validates structure according to IHE PAM 2.10 specifications, and provides human-readable explanations.

When to use this skill:

• Parse and explain any HL7 ADT message (raw HL7 text)
• Identify HL7 message type and event code (ADT^A01, ADT^A02, etc.)
• Extract and label all segments and fields (MSH, EVN, PID, PV1, PV2)
• Validate HL7 message structure and required fields
• Understand IHE PAM business rules and field mappings
• Debug HL7 message issues or data quality problems
• Document HL7 message examples with explanations

HL7 v2.5 Message Format

HL7 messages use specific delimiters:

Field delimiter:        |  (pipe)
Component delimiter:    ^  (caret)
Repetition delimiter:   ~  (tilde)
Escape character:       \  (backslash)
Subcomponent delimiter: &  (ampersand)

Basic Structure:

MSH|^~\&|SendingApp|SendingFacility|ReceivingApp|ReceivingFacility|Timestamp||MessageType|MessageControlId|ProcessingId|VersionId
EVN|EventTypeCode|RecordedDateTime|...
PID|SetId||PatientId||PatientName||BirthDate|Sex|...
PV1|SetId|PatientClass|AssignedPatientLocation|...

Segment Terminators: Each segment ends with carriage return (\r) or newline (\n)

IHE PAM Message Types

ADT Messages (Admit, Discharge, Transfer)

ADT^A01 - Admit/Visit Notification

Purpose: Patient admission to inpatient care or registration

Required Segments:

• MSH (Message Header)
• EVN (Event Type)
• PID (Patient Identification)
• PV1 (Patient Visit)

Example:

MSH|^~\&|HEXAFLUX|CHU_PARIS|TARGET|DEST|20260122140000||ADT^A01^ADT_A01|MSG001|P|2.5
EVN|A01|20260122140000|||USER001
PID|1||PAT12345^^^CHU_PARIS^PI||DUPONT^JEAN^^M.||19750315|M|||15 RUE DE LA PAIX^^PARIS^^75001^FRA||(33)612345678
PV1|1|I|CHU_PARIS^CARDIO^LIT_001^CHU_PARIS||||PR_MARTIN^MARTIN^SOPHIE|||CARDIO||||||||||VIS20260122001|||||||||||||||||||||||||20260122140000

Explanation:

• Event: A01 (Patient Admission)
• Patient: DUPONT JEAN (M.), born 15/03/1975
• Patient ID: PAT12345
• Visit: VIS20260122001
• Location: CHU_PARIS, Cardiology, Bed LIT_001
• Admission: 22/01/2026 14:00:00
• Patient Class: I (Inpatient)
• Attending: Dr. MARTIN SOPHIE

ADT^A02 - Transfer a Patient

Purpose: Patient transfer between units, rooms, or services

Required Segments:

• MSH, EVN, PID, PV1
• PV2 (optional but recommended for prior location)

Example:

MSH|^~\&|HEXAFLUX|CHU_PARIS|TARGET|DEST|20260123090000||ADT^A02^ADT_A02|MSG002|P|2.5
EVN|A02|20260123090000|||USER002
PID|1||PAT12345^^^CHU_PARIS^PI||DUPONT^JEAN^^M.||19750315|M
PV1|1|I|CHU_PARIS^NEURO^LIT_102^CHU_PARIS||||PR_DURAND^DURAND^PAUL|||NEURO||||||||||VIS20260122001
PV2||||||||||||||||||||||CHU_PARIS^CARDIO^LIT_001^CHU_PARIS

Explanation:

• Event: A02 (Patient Transfer)
• Patient: PAT12345 (DUPONT JEAN)
• From: Cardiology, Bed LIT_001 (PV2-1: prior location)
• To: Neurology, Bed LIT_102 (PV1-3: assigned location)
• Transfer Time: 23/01/2026 09:00:00

ADT^A03 - Discharge a Patient

Purpose: Patient discharge from hospital

Required Segments:

• MSH, EVN, PID, PV1

Example:

MSH|^~\&|HEXAFLUX|CHU_PARIS|TARGET|DEST|20260125180000||ADT^A03^ADT_A03|MSG003|P|2.5
EVN|A03|20260125180000|||USER003
PID|1||PAT12345^^^CHU_PARIS^PI||DUPONT^JEAN^^M.||19750315|M
PV1|1|I|CHU_PARIS^CARDIO^LIT_001^CHU_PARIS||||PR_MARTIN^MARTIN^SOPHIE|||CARDIO||||||||||VIS20260122001|||||||||||||||||||||||||||20260125180000|||||HOME

Explanation:

• Event: A03 (Patient Discharge)
• Patient: PAT12345 (DUPONT JEAN)
• Discharge Time: 25/01/2026 18:00:00 (PV1-45)
• Discharge Disposition: HOME (PV1-36)
• Visit: VIS20260122001

ADT^A04 - Register a Patient

Purpose: Pre-admission or outpatient registration

Required Segments:

• MSH, EVN, PID, PV1

ADT^A05 - Pre-admit a Patient

Purpose: Pre-admission notification

ADT^A06 - Change Outpatient to Inpatient

Purpose: Convert outpatient visit to inpatient admission

ADT^A07 - Change Inpatient to Outpatient

Purpose: Convert inpatient admission to outpatient visit

ADT^A08 - Update Patient Information

Purpose: Update patient demographics

Example:

MSH|^~\&|HEXAFLUX|CHU_PARIS|TARGET|DEST|20260122150000||ADT^A08^ADT_A08|MSG004|P|2.5
EVN|A08|20260122150000|||USER001
PID|1||PAT12345^^^CHU_PARIS^PI||DUPONT^JEAN^^M.||19750315|M|||15 RUE DE LA PAIX^^PARIS^^75001^FRA||(33)612345678|||||||1234567890123||FRA
PV1|1|O||||||||||||||||||||VIS20260122001

Explanation:

• Event: A08 (Update Patient Information)
• Patient: PAT12345 demographics updated
• Updated Fields: Address, phone, national identifier (NIR)

ADT^A11 - Cancel Admit

Purpose: Cancel a previous admission

ADT^A12 - Cancel Transfer

Purpose: Cancel a previous transfer

ADT^A13 - Cancel Discharge

Purpose: Cancel a previous discharge

Segment Definitions

MSH - Message Header (Required)

Purpose: Message metadata and routing information

Field Structure:

MSH|^~\&|SendingApp|SendingFacility|ReceivingApp|ReceivingFacility|Timestamp||MessageType^EventCode^MessageStructure|MessageControlId|ProcessingId|VersionId

Key Fields:

• MSH-3: Sending Application
• MSH-4: Sending Facility
• MSH-5: Receiving Application
• MSH-6: Receiving Facility
• MSH-7: Date/Time of Message (YYYYMMDDHHmmss)
• MSH-9: Message Type (ADT^A01^ADT_A01)
• MSH-10: Message Control ID (unique identifier)
• MSH-11: Processing ID (P=Production, T=Training, D=Debugging)
• MSH-12: Version ID (2.5)

EVN - Event Type (Required)

Purpose: Event-specific information

Field Structure:

EVN|EventTypeCode|RecordedDateTime|EventDateTime|EventReasonCode|OperatorId

Key Fields:

• EVN-1: Event Type Code (A01, A02, A03, etc.)
• EVN-2: Recorded Date/Time (when event was recorded)
• EVN-3: Event Occurred Date/Time (when event actually occurred)
• EVN-5: Operator ID (user who triggered the event)

PID - Patient Identification (Required)

Purpose: Patient demographic information

Field Structure (30+ fields):

PID|SetId||PatientId^^^AssigningAuthority^IdType~AltId||LastName^FirstName^MiddleName^Suffix^Prefix||BirthDate|Sex|PatientAlias|Race|PatientAddress||PhoneHome|PhoneBusiness|PrimaryLanguage|MaritalStatus|Religion|PatientAccountNumber|SSN|DriverLicense|MotherIdentifier|EthnicGroup|BirthPlace|MultipleBirth|BirthOrder|Citizenship|VeteranStatus|Nationality|DeathDateTime|DeathIndicator

Key Fields:

• PID-1: Set ID
• PID-3: Patient Identifier List (PatientId^^^Facility^PI)
• PID-5: Patient Name (LastName^FirstName^MiddleName^Suffix^Prefix)
• PID-7: Date of Birth (YYYYMMDD)
• PID-8: Sex (M/F/O/U)
• PID-11: Patient Address (Street^^City^^PostalCode^Country)
• PID-13: Phone Number - Home
• PID-14: Phone Number - Business
• PID-22: Ethnic Group
• PID-29: Death Date and Time
• PID-30: Death Indicator (Y/N)

PV1 - Patient Visit (Required)

Purpose: Visit/encounter information

Field Structure (52 fields):

PV1|SetId|PatientClass|AssignedLocation^Room^Bed^Facility|AdmissionType|PreadmitNumber|PriorLocation|AttendingDoctor^LastName^FirstName|ReferringDoctor|ConsultingDoctor|HospitalService|TemporaryLocation|PreadmitTestIndicator|ReadmissionIndicator|AdmitSource|AmbulatoryStatus|VIPIndicator|AdmittingDoctor|PatientType|VisitNumber|FinancialClass

Key Fields:

• PV1-1: Set ID
• PV1-2: Patient Class (I=Inpatient, O=Outpatient, E=Emergency, R=Recurring)
• PV1-3: Assigned Patient Location (Facility^Service^Room^Bed)
• PV1-4: Admission Type (E=Emergency, R=Routine, etc.)
• PV1-6: Prior Patient Location (for transfers)
• PV1-7: Attending Doctor (DoctorId^LastName^FirstName)
• PV1-10: Hospital Service
• PV1-19: Visit Number (unique visit identifier)
• PV1-36: Discharge Disposition (HOME, SNF, EXP, etc.)
• PV1-44: Admit Date/Time
• PV1-45: Discharge Date/Time

PV2 - Patient Visit - Additional Info (Optional)

Purpose: Extended visit information

Key Fields:

• PV2-1: Prior Pending Location (for transfers)
• PV2-3: Admit Reason
• PV2-8: Expected Discharge Date
• PV2-9: Expected Discharge Disposition
• PV2-47: Expected LOA Return Date/Time

IHE PAM Mandatory Fields

Required for All ADT Messages

• MSH-3: Sending Application
• MSH-4: Sending Facility
• MSH-7: Date/Time of Message
• MSH-9: Message Type
• MSH-10: Message Control ID
• MSH-12: Version ID (2.5)
• EVN-1: Event Type Code
• EVN-2: Recorded Date/Time
• PID-3: Patient Identifier
• PID-5: Patient Name
• PID-7: Date of Birth
• PID-8: Sex

Required for Admission/Transfer Messages (A01, A02)

• PV1-2: Patient Class
• PV1-3: Assigned Patient Location
• PV1-19: Visit Number
• PV1-44: Admit Date/Time

Required for Discharge Messages (A03)

• PV1-36: Discharge Disposition
• PV1-45: Discharge Date/Time

Parsing Logic

When asked to parse an HL7 IHE PAM message:

1. Split by segment terminator: segments = message.split('\r') or split('\n')

2. Parse MSH segment (always first):

   • Extract delimiters from MSH-2: ^~\&
   • Field delimiter: |
   • Component delimiter: ^
   • Repetition delimiter: ~
   • Escape character: \
   • Subcomponent delimiter: &

3. Identify message type: Check MSH-9

   • ADT^A01 = Admission
   • ADT^A02 = Transfer
   • ADT^A03 = Discharge
   • etc.

4. Parse each segment:

   • Split by field delimiter |
   • Parse components with ^
   • Parse repetitions with ~
   • Parse subcomponents with &

5. Extract key fields:

   • Patient ID (PID-3)
   • Patient name (PID-5)
   • Birth date (PID-7)
   • Visit number (PV1-19)
   • Location (PV1-3)
   • Dates (PV1-44, PV1-45)

6. Validate structure:

   • Check required segments present
   • Check required fields populated
   • Validate date formats (YYYYMMDD, YYYYMMDDHHmmss)
   • Validate code values (patient class, sex, etc.)

7. Generate explanation:

   • Identify message purpose
   • Explain event type
   • List key patient information
   • Describe visit/encounter details
   • Provide clinical context

Example Output Format

When parsing a message, provide:

### HL7 IHE PAM Message Analysis

**Raw Message**:

[original HL7 message with visible delimiters]

**Message Identification**:
- Message Type: ADT^A01
- Event Code: A01 (Admit/Visit Notification)
- Message Control ID: [MSH-10]
- Timestamp: [formatted MSH-7]
- Version: 2.5

**MSH - Message Header**:
- Sending Application: [MSH-3]
- Sending Facility: [MSH-4]
- Receiving Application: [MSH-5]
- Receiving Facility: [MSH-6]
- Processing ID: [MSH-11] (Production/Test)

**EVN - Event Type**:
- Event Code: [EVN-1]
- Recorded DateTime: [formatted EVN-2]
- Event Occurred: [formatted EVN-3]
- Operator: [EVN-5]

**PID - Patient Identification**:
- Patient ID: [PID-3]
- Patient Name: [formatted PID-5]
- Date of Birth: [formatted PID-7]
- Sex: [PID-8]
- Address: [formatted PID-11]
- Phone: [PID-13]
- [other relevant fields]

**PV1 - Patient Visit**:
- Patient Class: [PV1-2] ([description])
- Assigned Location: [formatted PV1-3]
- Attending Doctor: [formatted PV1-7]
- Hospital Service: [PV1-10]
- Visit Number: [PV1-19]
- Admit DateTime: [formatted PV1-44]
- [other relevant fields based on message type]

**PV2 - Additional Visit Info** (if present):
- Prior Location: [PV2-1]
- [other relevant fields]

**Business Context**:
[Explain what this message represents, the workflow event, and clinical significance]

**IHE PAM Compliance**:
- Required segments: [✓ or ✗ for MSH, EVN, PID, PV1]
- Required fields: [list of mandatory field validation results]
- Field formats: [✓ or ✗ for dates, codes, etc.]

Common ADT Event Codes

Code	Event Name	Purpose
A01	Admit/Visit Notification	Patient admission to inpatient care
A02	Transfer a Patient	Transfer between units/rooms
A03	Discharge a Patient	Patient discharge from hospital
A04	Register a Patient	Pre-admission or outpatient registration
A05	Pre-admit a Patient	Notification of planned admission
A06	Change Outpatient to Inpatient	Status change
A07	Change Inpatient to Outpatient	Status change
A08	Update Patient Information	Demographics update
A09	Patient Departing - Tracking	Patient left facility temporarily
A10	Patient Arriving - Tracking	Patient returned to facility
A11	Cancel Admit	Cancel previous admission
A12	Cancel Transfer	Cancel previous transfer
A13	Cancel Discharge	Cancel previous discharge
A21	Patient Goes on Leave of Absence	Temporary leave
A22	Patient Returns from Leave of Absence	Return from leave
A28	Add Person Information	Add new person to database
A31	Update Person Information	Update person demographics

Patient Class Codes

Code	Description
I	Inpatient
O	Outpatient
E	Emergency
P	Preadmit
R	Recurring patient
B	Obstetrics
C	Commercial Account
N	Not Applicable
U	Unknown

Discharge Disposition Codes

Code	Description
HOME	Home or self care
SNF	Skilled nursing facility
RH	Rehabilitation facility
EXP	Expired (deceased)
HOS	Hospice
AADVICE	Left against medical advice
OTH	Other

Validation Rules

Message Structure

• First segment MUST be MSH
• MSH-1 MUST be |
• MSH-2 MUST be ^~\& (encoding characters)
• Segments MUST be separated by CR or LF
• Fields MUST be separated by |

Required Segments by Message Type

• A01, A04, A05: MSH, EVN, PID, PV1
• A02: MSH, EVN, PID, PV1 (PV2 recommended for prior location)
• A03: MSH, EVN, PID, PV1
• A08: MSH, EVN, PID (PV1 optional)
• A11, A12, A13: MSH, EVN, PID

Date/Time Formats

• Date: YYYYMMDD
• DateTime: YYYYMMDDHHmmss or YYYYMMDDHHmmss.SSSS
• Time: HHmmss

Patient Identifier Format

• PID-3: PatientId^^^AssigningAuthority^IdentifierType
• Example: PAT12345^^^CHU_PARIS^PI

Name Format

• PID-5: LastName^FirstName^MiddleName^Suffix^Prefix^Degree
• Example: DUPONT^JEAN^^M.

Location Format

• PV1-3: PointOfCare^Room^Bed^Facility^LocationStatus^PersonLocationType^Building
• Example: CHU_PARIS^CARDIO^LIT_001^CHU_PARIS

Reference Documentation

IHE PAM Specification:

• French: https://github.com/Interop-Sante/ihe.iti.pam.fr
• International: https://profiles.ihe.net/ITI/TF/Volume1/ch-14.html

HL7 v2.5 Standard:

• Official: http://www.hl7.eu/HL7v2x/v25/std25/ch02.html
• Segments: http://www.hl7.eu/HL7v2x/v25/std25/ch03.html
• Data Types: http://www.hl7.eu/HL7v2x/v25/std25/ch02a.html

Related Tools:

• simple-hl7 (Node.js): https://github.com/Bugs5382/node-hl7-client
• HAPI (Java): https://hapifhir.github.io/hapi-hl7v2/

Quick Reference

Delimiters

|  Field delimiter
^  Component delimiter
~  Repetition delimiter
\  Escape character
&  Subcomponent delimiter

Common Fields

MSH-9  : Message Type (ADT^A01^ADT_A01)
MSH-10 : Message Control ID
EVN-1  : Event Type Code (A01, A02, etc.)
EVN-2  : Recorded DateTime
PID-3  : Patient ID
PID-5  : Patient Name
PID-7  : Birth Date
PID-8  : Sex
PV1-2  : Patient Class (I/O/E)
PV1-3  : Assigned Location
PV1-19 : Visit Number
PV1-44 : Admit DateTime
PV1-45 : Discharge DateTime