What is HL7?

Posted February 15, 2017
By George McLaughlin

L7 was created and is supported by the standards organization Health Level Seven International. HL7 is commonly used as a catchall, and most often, it refers to the data format and standards used at most healthcare organizations to structure and share medical data.

What is Health Level Seven International?

“Health Level Seven International is one of several American National Standards Institute (ANSI)—accredited Standards Developing Organizations (SDOs) operating in the healthcare arena. Most SDOs produce standards (sometimes called specifications or protocols) for a particular healthcare domain such as pharmacy, medical devices, imaging or insurance (claims processing) transactions. Health Level Seven’s domain is clinical and administrative data.”


What does Health Level Seven do?

HL7 provides standards for interoperability that improve care delivery, optimize workflow, reduce ambiguity and enhance knowledge transfer among all of our stakeholders, including healthcare providers, government agencies, the vendor community, fellow SDOs and patients. In all of our processes we exhibit timeliness, scientific rigor and technical expertise without compromising transparency, accountability, practicality, or our willingness to put the needs of our stakeholders first.


What is an HL7 Message?

An HL7 message includes information about a particular medical or administrative event. They are used to share data between disparate healthcare systems. An HL7 message looks like this:


PID|||56782445^^^UAReg^PI||KLEINSAMPLE^BARRY^Q^JR||19620910|M||2028-9^^HL70005^RA99113^^XYZ|260 GOODWIN CREST DRIVE^^BIRMINGHAM^AL^35209^^M~NICKELL’S PICKLES^10000 W 100THAVE^BIRMINGHAM^AL^35200^^O|||||||0105I30001^^^99DEF^AN
OBX|1|NM|^Body Height||1.80|m^Meter^ISO+|||||F
OBX|2|NM|^Body Weight||79|kg^Kilogram^ISO+|||||FAL1|1||^ASPIRINDG1|1||786.50^CHEST PAIN, UNSPECIFIED^I9|||AWhat is an HL7 Interface?

What is an HL7 Interface?

An HL7 interface is a data feed that allows the transmission of medical and administrative events in the healthcare setting to different systems. They are generally designated as inbound or outbound and are associated with different events that occur. Some common HL7 interfaces include ADT (admission, discharge, transfer events), SIU (scheduling events), MDM (media messages—pdfs, jpegs, etc.), ORM (results), and so on.

What is HL7 Version 2?

A nearly-30-year-old standard that is the most widely deployed healthcare data standard today. Commonly referred to as v2, it predates much of the technology you are using to read this article (http, xml, json, etc.) HL7v2 has a very wide scope of profiles defined ranging from orders/results to ADT and scheduling. In real world applications, 80% of the standard is written and consistent while 20% has been customized by implementers at each site it is in use.

What is HL7 Version 3?

Commonly referred to as v3, this standard is heavily concerned with removing the 20% ambiguity that implementers faced in v2. Despite covering most of the same profiles areas that v2 does, we don’t see many of these interfaces in the wild. Part of the reason for this may be the intense amount of work that was put into the defining resources—the dreaded Reference Information Model (RIM). Everything described by the RIM derives from three basic objects. This leads to a lot of inherited relationships that both frustrate developers and make the standard unreadable to humans. The theoretical model is sound, but a common criticism is that resulting product is too “academic”.

How Does HL7 Impact Integration with Redox?

As the most common standard in use today, many of our integrations utilize existing software systems that are formatted to HL7 standards. Many healthcare organizations utilize on premise HL7 interface engines to share data with disparate systems. We leverage this existing infrastructure to limit the amount of work required so that integrations can get approved and implemented quickly. Basically, if you are a healthcare organization that uses HL7 today, we’ll work with what you have in place and explain our integration workflow through language you are familiar with. For our digital health application customers, we distill the complexity of HL7 into easy to understand JSON objects we make publicly available. You only need to know as much about HL7 as you want to.

Common HL7 Interfaces Used in Redox Integration redox-hl7-interfaces.png

Learn More About HL7

When it comes to learning more about HL7, I would suggest going directly to the source. Health Level Seven does a great job providing detailed information and resources. Check them out at