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

Patient Class Codes

Discharge Disposition Codes

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