What Are HL7 and Their Types?

Ross Jackman | June 19, 2023

What Are HL7 and Their Types?

The term "Health Level Seven," or simply "HL7," refers to an international standard created by Health Level Seven International for the transmission of data (such as patient records, laboratory results, billing information, etc.) between software programs. This standard is also utilized by several healthcare providers. These standards are also adopted by other standard-setting organizations, including the International Organization for Standardization and the American National Standards Institute. With the aid of numerous testing phases, such as security testing, volume testing, etc., various organizations offering software QA services make sure that these criteria are being met.

An HL7 message refers to a hierarchical structure linked with a trigger event. The HL7 standard describes a trigger event as "an event in the real world of healthcare that initiates the need for data to flow among multiple systems". Big data in the healthcare market has this data of individual records as its integral part. This message includes a group of elements in a defined pattern. These segments or groups of segments are recursive, mandatory, or optional.

Following are the most frequently used HL7 message types:

  • RDE: Pharmacy/Treatment Encoded Order

    These messages are used to transmit instructions to a pharmacy or a system for administering medications. RDE messages comprise information like the medication or treatment ordered, dosages, frequency, route of administration, and other relevant clinical information.

  • ADT: Admit, Discharge, Transfer

    For HL7 communications, this message contains the patient's personal data as well as trigger events (such as the patient's registration, admission, discharge, transfer, etc.).

  • BAR: Billing Account Record

    BAR is a standardized way of extracting and exchanging billing information between different healthcare institutions. This record helps to ensure accurate and on-time billing and minimizes the likelihood of errors or discrepancies in billing between healthcare providers.

  • DFT: Detail Financial Transaction

    This message describes a financial transaction that is sent to a billing system and is used for patient accounting purposes.

  • MDM: Medical Document Management

    HL7 MDM message helps in managing the medical records by ensuring the latest documents/information is transferred to the centralized repository.

  • MFN: Master Files Notification

    The MFN message indicates if a record within the master file has been updated or replaced in its entirety.

  • ORM: Order Entry

    A new general order is created with the aid of this message. It includes every element of an order that was submitted to the Health Information System (HIS).

  • ORU: Observation Result (unsolicited)

    This message transmits the observation and results from the production system to the order system. This is a report in structured format where each observation is separated into an individual entity and then into fields.

  • ACK: Acknowledgement

    In health care data communications, there are two different forms of acknowledgment messages: HL7 ACKs (made using data from HL7 messages and in HL7 format) and non-HL7 ACKs (customer acknowledgment, which is merely a text string).

  • SIU: Scheduling Information Unsolicited

    This message apprises an auxiliary application of changes to some facet of the filler application's appointment schedule. It bestows a standard format for sending unsolicited updates about modifications to appointments, cancellations, rescheduling, or even new appointments.


This publication is for informational purposes only, and nothing contained in it should be considered legal advice. We expressly disclaim any warranty or responsibility for damages arising out of this information and encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.

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