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What HL7 messages should a PACS Administrator learn?

PACS Training - HL7 Basics 101

It is important for a PACS administrator or any radiology IT analyst to understand the basic concepts of HL7.  However this may sound like a daunting or challenging task as there are many different types of HL7 messages.  This module will describe what specific HL7 messages are relevant to the radiology workflow.  The goal is to simplify HL7 for anyone working in the imaging informatics field. 

We will first define the HL7 standard, HL7 interface and what an HL7 message is. We will then review ADT, ORM and ORU messages and how they apply to radiology.

HL7 Basic Recap

HL7 (Health Level Seven) is a set of international standards meant to facilitate the exchange, integration, sharing, and retrieval of electronic health information. It establishes a structure and set of rules for the formatting, transmission, and interpretation of healthcare data, ensuring interoperability among various healthcare systems. HL7 is frequently used in healthcare environments to facilitate seamless data interchange and communication across various healthcare apps and equipment.

What is an HL7 Interface

An HL7 interface engine, often called an integration engine or HL7 broker, is a piece of software that functions as a central hub for controlling the flow of HL7 communications between various healthcare systems. Think of the HL7 interface as the middle-man or broker that sits in the center of all healthcare applications.  All HL7 messages must first pass through the middle-man before reaching the destination application.  The middle-man ensures the content of the message is standardized and will be readable by the receiving application.  Examples of HL7 interface engines are Mirth Connect, Corepoint Integration Engine, Infor Cloverleaf, Intersystems Ensemble and Orion Health Rhapsody. 

By translating and forwarding HL7 messages to the proper systems or applications, Interface engines act as a mediator, enabling the information exchange. The interface engine is essential for connecting various healthcare systems, including electronic medical record (EMR) systems, picture archiving and communication systems (PACS), radiology information systems (RIS), laboratory information systems (LIS), and more.  

For most PACS admins, the HL7 communication between the following systems will be most helpful to be aware of:  The EMR, PACS, RIS, Voice dictation system and various related radiology applications.  The data flow of messaging between these systems will be covered in a separate module.

What are HL7 messages?

An HL7 message is structured in a standardized format for exchanging healthcare information. It functions as an organized data package that includes specific types of data on patient demographics, clinical observations, orders, outcomes, and other healthcare-related information. Systems are able to accurately interpret and process data between each other because HL7 communications adhere to a prescribed format and structure.

Now that we understand the basics, let’s review which messages should PACS administrators pay attention to.

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Important HL7 messages for PACS admins

ADT, ORM, and ORU are specific message types that serve different purposes. 

Admission, Discharge, and Transfer, or ADT, is a term used to communicate patient demographic and administrative data. It contains information about the patient’s identification, the reason for admission, the location, the attending physician, and insurance details. The management of bed assignments, organizing care transitions, and updating patient records all depend on ADT communications.

Order Message or ORM, is used to transmit orders for clinical services or procedures. It contains information about the patient, the requested service, pertinent dates, and other specifics required for carrying out the order. Common uses of ORM messages include ordering prescription drugs, scheduling laboratory tests, and requesting radiology exams..

Observation Result Message or ORU, is used to transmit the results of clinical observations or tests. It contains test results, measurements, interpretations, and other pertinent information. Laboratory results, radiography reports, pathology findings, and other diagnostic information are shared via ORU messages.

Now that we understand ADT, ORM and ORUs, let’s see how this data is used throughout a radiology workflow.

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HL7 data flow in Radiology

To reiterate; In an integrated healthcare environment, HL7 messages play a vital role in connecting different systems such as the EMR, PACS, and Voice Dictation System. Let’s explore the flow of HL7 messages from when a patient is admitted to the completion of a radiology exam.

When a patient is admitted to a hospital, an ADT message is sent from the EMR to update the patient’s demographic and admission information. This message is sent from the EMR to the HL7 interface engine which sends it to the respective downstream systems such as the PACS and the RIS. This updates the patient’s information within these systems, ensuring proper identification and organization of radiology images.

A physician may place an order for a radiology exam through the EMR. An ORM message is sent from the EMR to the HL7 interface. Then to the RIS, PACS and Voice Dictation System. The RIS system receives the ORM message which integrates into the corresponding imaging modality.  This allows for a DICOM modality worklist to streamline the order data into the medical images.  This is explained in more detail in the DICOM MWL module.  

After imaging is captured and reviewed by a radiologist, the radiologists will dictate a final result into the Voice Dictation System.  The interpretation and findings are captured in an ORU message.  This ORU message is sent from the voice dictation system back to the HL7 interface which forwards it ultimately to the EMR. This allows for the final result to be included in the patient’s medical record and made available to the referring physician. PACS can also receive the ORU to display the final report alongside the medical images.

Read more about how these ORMs and ORUs are used in radiology applications here.

Note that in the example provided above, the HL7 messages are not sent directly from one system to another. Rather the messages actually pass through the interface engine first. As stated earlier, this is to ensure the appropriate systems receive the correct messages in a standardized format.  The HL7 broker can transform any incorrect data.  It can also push messages to multiple receiving systems if needed.  

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Wrapping up

In summary, HL7 is a set of standards for healthcare data exchange, an HL7 interface engine facilitates the communication between different systems, and ADT, ORM, and ORU are specific message types used for different purposes. HL7 messages are crucial for seamless data exchange between the EMR, PACS, and Voice Dictation System, enabling efficient patient care coordination and accurate documentation of healthcare information.

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