# Introduction to HL7

## Purpose

This lesson will introduce you to the HL7v2 standard, which is used to exchange data between healthcare IT systems. After you have completed this lesson, you will be familiar with a few core concepts. You will also know where to look for more information.

## Learning Material

Read through sections 1.3, 1.4, 1.5, and 1.8 of chapter 1 of the HL7 v2.9 standard. We have a copy in the HL7 directory in the Innolitics Library. You can also download a copy on the HL7 website after creating a free account.

Watch this short video about the HL7 message format.

Browse through sections 2.2, 2.3, and 2.4 of chapter 2 of the HL7 v2.9 standard. Chapter 2 describes the message format from the previous video in a good deal more detail.

Glance through chapters 2A (Data Types) and 2C (Code Tables).

Glance through the Caristix “HL7 Survival Guide” in the root of the Innolitics Library. You can also view the guide on the Caristix website here or download a copy here. Chapters 5, 6, and 12 may be particularly relevant.

## Exercises

To learn as much as possible from these exercises, write your responses before revealing the provided answers. If any exercises seem irrelevant, you can skip them and instead write a justification as to why they are unimportant. These justifications will help us improve the lesson for future employees.

### Exercise 1

Define, in your own words, the following HL7 terms: “trigger event”, “message”, “segment”, “field”, “data type”, “component”, and “sub-component”.

### Exercise 2

Consider this HL7 message.

``````MSH|^~\&|SWSIMAGESRVR|INNOLITICS_ENG|MIRTH|INNOLITICS_ENG|20100719171917.926||
ORU^R01^ORU_R01|1279585157566|P|2.6||||||UNICODE UTF-8
PID|1||SWS-F4263E6F||EXAMPLE^JOSEPHINE^DEVA||19641102|F
OBR|1|899911-333^fred|00112781^SWS_FILLERUP|077777-TCD^077777-TCD^DEFAULT_RSCSN|||
20090923155556|||||||||^KENOBI|||||||||F|||||||&DaRavino&Alfonse&&&&C.A.
OBX|1|ED|EncapsulatedReport^1.2.840.114340.3.8251016058117.2.20090923.155556.44||
fred^application^application/pdf^Base64^<Base64 Encoded PDF>||||||F
``````

NOTE: The lines were hardwrapped to avoid the need for horizontal-scrolling. Ordinarily there is one HL7 segment per line.

What is the message type? What do the components of the message type field mean?

### Exercise 3

Select another field from the HL7 message in Exercise 2 and track down what it means.

### Exercise 4

Using the Caristix HL7 browser (in many ways analogous to our DICOM Standard Browser, but for HL7), look up the MSH segment for HL7v2.6. Then look up the Message Type field. Then look up the possible values for the Message Code component.

### Exercise 5

Click on the “HL7 Messaging” tab on the left side of the Caristix HL7 tool. Create an account. Then upload the sample message from Exercise 2. Be sure to remove the hardwrapped line breaks and select the right version of the standard from the dropdown. Look up the same field you investigated in Exercise 3 using this tool.