Types of HL7 ADT message and an example of ADT^A04 (2024)

In the previous article, we'vediscussed the originof 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 ADTmessages (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.

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

[ ] = optional segment, { } = repeating segment

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

Example ofHL7 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||||202211030800PID||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.

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

Any comments/suggestions are welcome in the comments section.