Although most of this book is primarily about the BizTalk Accelerator, you first need to understand what the HL7 is and what the HL7 standards are all about. This chapter will serve as an introduction to these standards and will also provide you with a foundation that will make it easier for you to understand the topics in all the chapters.

Before you take a look at the HL7 standards, you should know a little bit about HL7 (Figure 1-1). Since HL7 can do a better job describing itself then we can, the following sections contain excerpts from the HL7 web site (www.hl7.org/about/index.cfm?ref=nav).

What Is HL7?

Health Level Seven International (HL7) is a not-for-profit, ANSI-accredited, standards-developing organization. HL7 is dedicated to providing a comprehensive framework and related standards for the exchange, integration, sharing, and retrieval of electronic health information. HL7 supports clinical practice and the management, delivery, and evaluation of health services.

What Does HL7 Mean?

What Is the Open Systems Seven-Layer Communications Model?

The HL7 organization describes this model as follows:

Introduction to HL7 Standards

HL7 and its members have worked over the years to provide world-wide healthcare with a framework that includes related standards. The standards are for the exchange, integration, sharing, and retrieval of electronic health information.

• The HL7 standards define how this information is packaged and communicated from one party to another.
• The HL7 standards also set the language, structure, and data types that are required to provide a seamless integration between systems.
• HL7 standards provide support for the following:
  • Clinical practice of health services
  • Management of health services
  • Delivery of health services
  • Evaluation of health services

• The HL7 standards are recognized as the most commonly used in the world.

Seven Referenced Categories

HL7 standards are grouped into seven reference categories or sections. The HL7 organization describes these as follows:

• Section 1: Primary Standards: The primary standards are the most popular standards integral for system integration and interoperability.
• Section 2: Foundational Standards: The foundational standards define the fundamental tools and building blocks used to build the standards, and the technology infrastructure that implementers of HL7 standards must manage.
• Section 3: Clinical and Administrative Domains: Messaging and document standards for clinical specialties and groups are found in this section.
• Section 4: EHR Profiles: These standards provide functional models and profiles that enable the constructs for management of electronic health records.
• Section 5: Implementation Guides: This section is for implementation guides and/or support documents created for use in conjunction with an existing standard.
• Section 6: Rules and References: These are technical specifications, programming structures, and guidelines for software and standards development.
• Section 7: Education & Awareness: You can find HL7’s Draft Standards for Trial Use (DSTUs) and current projects here, as well as helpful resources and tools to further supplement understanding and adoption of HL7 standards.

We could describe these categories in more detail, but that is not what this book is all about. Besides, the HL7 organization does a much better job at it than we ever could. If you want to read more about these standards, you can access the information directly at www.hl7.org/index.cfm?ref=nav.

The HL7 Versions

Although there are several versions published by the HL7 organization, we will be concentrating on HL7 Version 2 Product Suite of the HL7 Primary Standards. The HL7 Version 2 Product Suite is part of Section 1 of the HL7 standards. The reason for the name primary standards is due to its popularity, since it is the most frequently used standard today.

Many in the global healthcare industry say that “HL7’s Version 2.x (V2) messaging standard is the workhorse of electronic data exchange in the clinical domain,” as stated in the HL7 – Standards – Master Grid documentation. In addition, according to the HL7 – Standards – Master Grid documentation, several healthcare publications have described HL7 Version 2.x as the “most widely implemented standard for healthcare in the world.”

It is designed to support the following:

• A central patient care system
• A distributed environment where data resides in departmental systems
• A distributed environment where data resides in multiple repositories

Key Benefits of Version 2.x

The key benefits provided by Version 2.x are the following:

• Supports the majority of common interfaces used in the global healthcare industry.
• Provides a framework for negotiating what is not in the standard.
• Greatly reduces implementation costs.

HL7 Version 2.x Message Structure

In the last two sections you were introduced to the HL7 organization and its standards and versions. Moving forward, let’s take a high-level look at the HL7 Version 2.x message structure.

To help you understand the message structure, you need to take a closer look at the components that make up the message structure:

• Delimiters
• Segments
• Fields
• Data Types
• Escape Sequences

One of these key components is the segment. Let’s take a brief look at the segment.

Segment

A segment is a logical grouping of data fields that represents a collection of related and unique information. A HL7 Version 2.x message can contain multiple segments. Segments can also contain child segments, commonly referred to as subsegments. These too can contain child segments.

Let’s take a look at a common message structure. Figure 1-2 shows the message structure for the Admit/Visit Notification message type. This is a very commonly used message. You will be learning more about this and other message types in Chapter 2.

At the top of the message structure is a MSH segment. This is the message header segment and is required in all HL7 messages. Your knowledge of what is contained within this segment will make it easier to understand the technical terminology used throughout this book. Going forward, we will refer to this segment using its three letter identifier, MSH.

Contained within each segment are predefined data types. Let’s take a look at the data types for the MSH segment.

The MSH Segment Data Fields

There are 21 data fields in the MSH segment. These are identified by a sequence number. Table 1-1 will make it easier for you to understand what each sequence number represents. The values in the R/O/C column are R = Required, O = Optional, and C = Conditional.

As you can see, the descriptions are fairly easy to understand. But there is more to the data fields. The HL7 Version 2.x standard contains many different data types. There are both simple and complex types. You will learn more about the data types in Chapter 2.

Moving Forward

Now that you have learned a little bit about the HL7 Version 2.x message structure, let’s see what you will learn about in the rest of the chapters.

As previously mentioned, in Chapter 2, you will learn all there is to know about HL7 Version 2.x message encoding. You will also learn about the rest of the components that make up the HL7 Version 2.x message structure.

In Chapter 3, you will learn all about the accelerator’s capabilities.

In Chapter 4, you will view a few scenarios that will show you how to use the accelerator.

As previously mentioned, in Chapter 5, you will be presented with three scenarios. One of these scenarios was taken from a recently implemented solution.

In Chapter 6, you will get a preview of the new HL7 standard that the HL7 organization is currently working on.

Chapter 7 will provide you with best practices.

Summary

This chapter provided you with an introduction to HL7. You were also introduced to the HL7 Version 2.x standard. You had a quick look at the HL7 Version 2.x message structure and learned a little about the MSH segment. And finally, you had a glimpse of what the rest of the chapters are all about.