Information standardization is the key to effective clinical data sharing between hospitals and different systems in a healthcare organization. 

According to statistics, an average medical institution uses 16 diverse software systems. With more than 500 vendors using different technologies, hospitals struggle to exchange clinical data between various systems.

In order to facilitate data interoperability, the HL7 EHR functional model was developed. These days, HL7 standards are widely adopted by many organizations and healthcare software development vendors. In the post below, you will discover what HL7 EHR rules are and what their purpose is.


Health Level Seven (HL7) is a set of rules and standards that help standardize clinical data for establishing information interchangeability. 

By following the HL7 EHR rules, healthcare organizations standardize all the information and its structure. The approach foresees the opportunity to connect different solutions with EHR systems developed by using various technologies. The HL7 EHR functional model complies with most health data transferring policies, keeping confidential data unexposed.

HL7 Vision: A world in which everyone can securely access and use the right health data when and where they need it.


Let's elaborate on the HL7 EHR data standards to better understand how they work. The number 7 in the standard's name refers to the layer it applies to in the OSI model. It includes the following layers:

  1. Physical — A physical network connection like Ethernet cables, WiFi connection, etc.
  2. Data link — Data format definition.
  3. Network — Network management and data routing.
  4. Transport — Data flow maintenance.
  5. Session — Ports and sessions control for session management. 
  6. Presentation — Data translation, including encryption/decryption, data compression, etc.
  7. Application — End-user application with network access.

Developers can use different technologies to implement solutions on layers 1-6. The HL7 data interoperability rules are used on the application layer only.

The HL7 EHR functional model enables healthcare systems to exchange data using messages formatted according to specific clinical data standards. Different software solutions can be connected using an integration engine that turns domain-specific data into HL7 messages.

Develop HL7-enabled software

There are dozens of HL7 message types that help share different kinds of health data. The ten most common types of HL7 V2 messages are the following.

HL7 Message Type HL7 Message Name Description
ADT Admit, Discharge, and Transfer Information about patients in a healthcare facility, events related to patients, personal data updates, etc.
ORM Order Entry It is a request message type that initiates the transfer of requested details.
ORU Observation Result A message that implies the observations results of a patient, including lab reports, radiology results, EKG studies, etc.
MDM Medical Document Management This type of HL7 message enables healthcare organizations to transfer medical documents efficiently, receive change updates, change statutes, etc. 
DFT Detailed Financial Transactions It helps transfer financial information about charges, insurance, billing accounts, charges, and other details to a billing department.
BAR Billing Account Record This message type helps create new billing accounts, change, and delete them.
SIU Scheduling Information Unsolicited It is used to share information about patients' appointments. Also, it can be used to schedule appointments, reschedule or cancel existing ones.
RDE Pharmacy/Treatment Encoded Order Messages that help doctors submit pharmacy orders and send them to pharmacy dispensing systems fast.
RDS Pharmacy/treatment Dispense It is a response message from a pharmacy to notify a healthcare organization about a fulfilled order.
ACK Acknowledgment Message This response message indicates the status of submitted requests or errors that occurred if a recipient didn't receive a message.
Read also:

Versions of HL7 EHR Standards

Many versions of HL7 EMR (electronic medical records) rules use different approaches to health data transferring. HL7 standards define how documents are structured, what data types are used, and what languages are utilized.

HL7 standards

The four primary HL7 data standards are the following:

  • HL7 Version 2. Many 2.X versions are compatible with each other. HL7 V2 messages are composed by using defined rules and symbols to share clinical data efficiently. It is a legacy standard that lacks some features.
  • HL7 Version 3. It is a newer version of the HL7 standards that implies additional features. It uses XML to share messages. Vocabulary data standards, domain-specific modules, and standardized clinical data types are some features of this HL7 standards version. Healthcare providers didn't widely adopt the version because it is not backward compatible with the 2.X versions.
  • CDA. It is the document creation standard that defines rules for composing medical documents. CDA documents have a human-readable format and use defined terminology to achieve semantic interoperability. Documents are structured by using certain standards and are created using templates.
  • FHIR. The HL7 Fast Healthcare Interoperability Resources standard is the newest one with many forward-looking features. Structured messages are shared by using APIs. The newest standard enables the opportunity to share clinical data in live time, supports different formats, has a modular structure, and can work with many applications.
Develop Innovative Healthcare Solutions that Use HL7 Standards


The HL7 standards help medical organizations connect systems with different purposes and are built using distinctive technologies.

HL7 usage in healthcare

For instance, the rules enable patients, medical staff, and authorized third parties to connect a hospital information app with the following systems:

  • Electronic medical record (EMR)
  • Electronic health record (EHR)
  • Radiology information system (RIS)
  • Lab information management system (LIMS)
  • Billing system

Let's check use scenarios to discover how HL7 standards help facilitate health data exchange in real-world environments.

Use Scenario #1: Appointment Check

Let's check how HL7 standards help patients verify their appointment using a terminal in a medical institution in more detail.

Appointment check with HL7

The data flow of the use scenario implies the following actions:

  1. A patient enters authorization details and requests appointment data using on-site kiosks in a hospital.
  2. Requests are sent to the hospital information system.
  3. A web service request is sent to an HL7 data integration engine.
  4. An HL7 ORM (Order Entry) message is sent to an EMR system.
  5. An HL7 SIU (Scheduling Information Unsolicited) message is returned.
  6. A web service response message is sent to the hospital information system.
  7. Appointment information is delivered to the patient using the kiosk's interface.

Use Scenario #2: Radiology Results Request

A doctor requests the radiology results of a patient by using a hospital information system.

Radiology results request with HL7

The data flow implies the following stages:

  1. A doctor uses an EHR system to request radiology results from a RIS.
  2. A web service request is passed to an HL7 integration engine.
  3. The request is transformed into an HL7 ORM (Order Entry) message and is sent to a RIS.
  4. An HL7 ORU (Observation Result) message is sent to the data integration message.
  5. An EHR system receives a web service response from the engine. 
  6. The radiology results are saved in the EHR system and are analyzed by the doctor.

Use Scenario #3: Prescription Ordering

A doctor submits a prescription order that is sent to a pharmacy dispensing system automatically.

Prescription ordering with HL7

The data flow implies the following stages in this use scenario.

  1. A doctor submits a prescription order using an EHR system.
  2. A web service request is sent to an HL7 integration engine. 
  3. The request is transformed into an HL7 RDE (Pharmacy/Treatment Encoded Order) message and is sent to a pharmacy.
  4. Once the order is fulfilled, a response in the form of an HL7 RDS (Pharmacy/Treatment Dispense) message is returned. 
  5. The response HL7 RDS message is transformed into a web service request and is sent to the EHR system.
Need a custom solution for medical organization?


More than 95% of healthcare organizations are about to keep investing in interoperability development or increase their spending due to the many benefits. Let's check the foremost advantages of interoperability promotion.

Smooth Integration of Different Systems

The usage of HL7 standards enables healthcare organizations to interconnect a lot of systems from different vendors, regardless of the technologies they use. 

For example, a hospital can choose a hospital information system (HIS), billing system, and laboratory information management system (LIMS) from different providers and integrate them into one solution for managing patients' data.

Better Data Quality

Thanks to standardization, medical organizations can improve the quality of their data. The adoption of HL7 standards needs hospitals to share messages that match defined standards. Also, they can use templates to create documents for sharing. They can verify and change data shared between different systems using an integration engine through the EMR HL7 interface.

Improved Collaboration

HL7 standards allow medical organizations to share health data to improve patient care coordination. Clinical data interoperability enables different medical institutions to fetch electronic health records from other hospitals or labs so that patients don't need to bring lab analysis results or medical records.

HL7 Mission: To provide standards that empower global health data interoperability.

Reduced Number of Errors

Since documents or messages are created by following HL7 rules, hospitals can reduce the number of errors caused by human factors. 

Besides, the HL7 standards enable medical staff to ensure that messages are delivered. For instance, when using the EMR HL7 interface, systems share the Acknowledgement Message (ACK) to ensure a message is successfully delivered. Otherwise, users receive response messages about failed message delivery and errors.

Improved Compliance

By implementing HL7-driven digital solutions, hospitals can access a framework that helps securely share digital health information, complying with HIPAA regulations.

The Affordable Care Act (ACA) requires healthcare institutions to exchange health information between different systems electronically. Using HL7 standards, they can seamlessly integrate solutions from different providers into one system to meet all the requirements. 

Health Information Exchange Automation

Healthcare organizations widely adopt the HL7 data standards due to the many benefits they offer.

For instance, using HL7 standards, healthcare organizations can develop systems where an electronic health record (EHR) system automatically fetches data from a laboratory information management system (LIMS) when a test is completed.

Read also:


The HL7 standards are widely adopted by healthcare organizations due to the many benefits they offer.

Data interoperability statistics

Take a deeper look at the state of health data interoperability by examining overall health data interoperability statistics.

  • The data interoperability market size is estimated to reach the $21.5 billion milestone by 2030 at a CAGR of 14.9%, according to Allied Market Research.

Explore the major problem that patients face due to the lack of data interoperability in medical organizations by checking the statistics that are gathered by the National Coordinator for Health Information Technology (ONC).

  • 19% of patients had to bring their prior lab test results to an appointment because a doctor couldn't access them remotely.
  • 32% of patients experienced challenges due to the lack of data interoperability in healthcare organizations.

Also, let's discover what healthcare executives think by checking the statistics below. 

  • Google states that 75% of healthcare executives state that data interoperability adoption is one of the top priorities in their medical organizations.
  • According to the research conducted by the Google Cloud team, 92% of doctors think that health data interoperability helps improve the patient experience.
  • Insider Intelligence found that more than 50% of healthcare organizations plan to increase their spendings on data interoperability adoption year-to-year.


The HL7 EHR framework sets standards that enable medical organizations to share health data fast and error-free. The main objectives of implementing these data interoperability standards are as follows:

  • Integrate HL7 data from EHR system
  • Comply with regulatory requirements
  • Improve patients experience

There are many versions of HL7 standards. The FHIR is the newest one. It foresees the opportunity to connect systems using APIs and share health data in live time. HL7 messages are composed by following defined rules. Medical documents shared between different systems have a specific structure and can be created using templates.

Hire HL7 software development experts
What are HL7 standards?

HL7 is a set of standards that help share and retrieve health data. Messages composed of defined rules can be exchanged by digital systems that use different technologies.

How is HL7 used in healthcare?

Usually, HL7 messages are used to connect many diverse digital solutions from different vendors into one system. Also, the use of HL7 standards enables medical institutions to share information with other hospitals, insurance companies, or regulatory agencies.

What are the top versions of HL7 messaging standards?

Three primary versions of HL7 messaging standards are the following:

  • HL7 V2 — the most widespread version
  • HL7 V3 — an enhanced version of the HL7 V2
  • HL7 CDA — medical documents creation markup
  • HL7 FHIR — the newest version
What are the benefits of HL7 EMR interoperability?

There are many benefits of adopting the HL7 standard to enable health data interoperability. The foremost advantages are the following:

  • Smooth data integration across different systems
  • Better clinical data quality
  • Reduced errors
  • Improved HL7 compliance
  • Automated health information exchange
  • Improved collaboration
What is the HL7 EHR functional model?

The HL7 EHR functional model is a framework for message creation and medical document creation. In a nutshell, it is a set of rules that help create unified messages exchanged between systems that use different technologies.

Let's discuss your project

Best Upwork agency 2015, 2016, 2018
Member of the Clutch 500
Top automation testing companies
Top 50+ Ukraine Based Mobile App Development Companies In 2020
Top iPhone and iOS mobile app developers 2020

related posts