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An ADT message is an HL7 message created by healthcare information systems when an ADT event occurs. ADT stands for admission, discharge, transfer. In essence, an ADT event is an important event that transpired when a patient gets admitted, discharged, or transferred from one clinic/hospital to another or the patient’s home. Typically, ADT messages are triggered from an EMR/EHR, and they contain patient demographic, diagnostic, and insurance information. This article will take a brief look at how to manually construct a HL7 ADT message types for a simple admission into a hospital. Note that specialized tools will be used to create, format, parse, and send such messages in actual practice.

1. Know the Structure of HL7 ADT Message Types

For HL7 version 2.3 and older, there are many ADT message types and events. Examples include:

  • A01 Admit/visit notification
  • A02 Transfer a patient
  • A03 Discharge/end visit
  • A04 Register a patient
  • A05 Pre-admit a patient

For instance, if we take the A01 event (admit notification), the HL7 standard recommends a definite structure for the message. For an ADT-A01, the structure is as follows:

MSH Message Header

EVN Type of Event

PID Patient Identification

NK1 Next of Kin

PV1 Patient Visit

OBX Observation/Result

AL1 Allergy Data

DG1 Diagnosis

PR1 Procedures

GT1 Guarantors Information

IN1 Insurance Information

ACC Accident Data

UB1 Universal Bill Information

Note that the following segments are required while others are optional:

The message header (MSH), event (EVN), patient identification (PID), next of kin (NK1), and information about the patient visit (PV1).

In HL7 messages, the pipe character “|” is the separator for each field. The caret ^ is the space character. Bear in mind that a single carriage return separates each message segment.

2. Construct Message Segments

Next, we will construct the mandatory message segments one after the other, starting with the MSH segment.

MSH Segment

Just like you have address fields in an email message, in the MSH Segment, the following fields need to be filled:

From: [ the system, location ]

To: [ the system, location ]

When: [ the date, time ]

Msg Type: [type of HL7 message ]

Msg ID:

HL7: [ version number ]

An example of an HL7 encoded MSH message segment is:

MSH | | CERNEREHR | NY | LABLIS | NY | 202102021310 | |ADT^A01|0000012|P|2.3.1|

The EVN Segment

The event segment requires the following fields to be filled:

Type: [ admit, discharge, or transfer ]

When: [ date, time ]

After checking mapping tables, we can have this encoded EVN message segment:

EVN | A01 | 202102021310| |

The PID Segment

The patient identity segment is usually the longest in this type of ADT message. The important fields to fill in are:

ID: [ Unique identifier ]

Name: [ Full name ]

DOB: [ date of birth ]

Address: [ street address ]

Contact: [ Phone etc. ]

A sample encoding of the PID segment is:

PID | | | 0009876 | | SMITH^DAVID | | | 19750305 | M | | C | 1^10TH^AVENUE^^LIBERTY^CITY^MIAMI^FL^75020 | GL | (212)567-1313 |

The PV1 Segment

The patient visit information contains the following fields:

Where: [ location, room, and bed ]

Who: [ provider identifier, provider name ]

Admit Type: [ surgery, physiotherapy, etc.]

Encoding the patient visit segment with the following sample data:

Location: Unit 105, Room # 14, Bed # 05,

Provider: John K. Lake, NPI #000567

Admit Type: Surgery.

Encoding this data into a PV1 message segment will give us this:

PV1 | 1 | I | 105^14^05 | | | | 000567^JOHN K. LAKE | | | SUR | | | | ADM | A01 |

Location can give this:

PV1 | 1 | I |

3. Combine the Message Segments

After creating the individual message segments, we have to merge them to make a complete HL7 message. Using the sequence in the ADT structure, we have our HL7 ADT-A01 message looking like this:

Note that some of the carriage returns have been omitted from the message segments.

MSH | | CERNEREHR | NY | LABLIS | NY | 202102021310 | |ADT^A01|0000012|P|2.3.1|

EVN | A01 | 202102021310| |

PID | | | 0009876 | | SMITH^DAVID | | | 19750305 | M | | C | 1^10TH^AVENUE^^LIBERTY^CITY^MIAMI^FL^75020 | GL | (212)567-1313 |

PV1 | 1 | I | 105^14^05 | | | | 000567^JOHN K. LAKE | | | SUR | | | | ADM | A01 |

That was a sample ADT message showing some of the most commonly used segments. This was provided strictly for informational purposes. In practice, you will have to use a tool to create, encode and send your message.

Connect With an Expert HL7 Developer

If you need to create HL7 ADT message typess or are interested in developing HL7 interfaces for your practice or organization, get in touch with us today. Call Lifepoint Informatics at 877.522.8378 or visit our contact page now to book a free consultation.