What is HL7 and Why Does Healthcare Need It?

By Biswanath Sahoo

In today’s digital healthcare environment, hospitals and healthcare organizations rely on dozens of different software systems. Patient registration systems, electronic medical records (EMRs), laboratory systems, pharmacy applications, radiology platforms, and billing systems all generate and consume critical patient information. But how do these systems communicate with one another?

The answer is HL7 (Health Level Seven).

Understanding HL7

HL7 is a set of international standards designed to facilitate the exchange, integration, sharing, and retrieval of electronic health information. It enables different healthcare applications to communicate seamlessly, regardless of the vendor or technology used.

Think of HL7 as a common language that allows healthcare systems to understand each other.

Without HL7, hospitals would struggle to share patient information efficiently, leading to delays, errors, and increased operational costs.

Why Was HL7 Created?

Healthcare organizations use multiple applications from different vendors. For example:

• Patient Registration System
• Electronic Health Record (EHR)
• Laboratory Information System (LIS)
• Radiology Information System (RIS)
• Pharmacy Management System
• Billing System

Each system stores data differently. HL7 provides a standardized format that enables these systems to exchange information accurately and consistently.

Example

When a patient is admitted to a hospital:

1. Registration staff enter patient details.
2. An HL7 ADT (Admission, Discharge, Transfer) message is generated.
3. The message is sent to other systems.
4. The laboratory, pharmacy, and billing systems automatically receive the patient’s information.

This eliminates manual data entry and reduces the risk of errors.

What Does HL7 Stand For?

HL7 stands for Health Level Seven.

The “Level Seven” refers to Layer 7 (Application Layer) of the OSI (Open Systems Interconnection) model, which focuses on communication between software applications.

HL7 is not a software product. It is a standard that software vendors use to exchange healthcare information.

Common HL7 Message Types

HL7 Version 2 uses messages to communicate healthcare events.

Some of the most common message types include:

ADT (Admission, Discharge, Transfer)

Used for patient registration and demographic updates.

Examples:

• ADT^A01 — Admit Patient
• ADT^A03 — Discharge Patient
• ADT^A08 — Update Patient Information

ORM (Order Message)

Used to send orders such as laboratory tests or imaging requests.

ORU (Observation Result)

Used to send laboratory or diagnostic results.

SIU (Scheduling Information)

Used for appointment scheduling.

A Simple HL7 Message Example

MSH|^~\&|EHR|Hospital|LAB|LabSystem|202606210900||
ADT^A01|12345|P|2.5

Key Segments

MSH (Message Header)

• Contains sender information
• Contains receiver information
• Defines message type

PID (Patient Identification)

• Patient ID
• Name
• Date of Birth
• Gender

Each segment contains important information used by receiving systems.

Benefits of HL7

1. Improved Patient Care

Healthcare providers can access accurate and up-to-date patient information quickly.

2. Reduced Errors

Automated data exchange eliminates duplicate data entry and reduces human errors.

3. Faster Communication

Information is delivered in real time between healthcare systems.

4. Operational Efficiency

Staff spend less time manually transferring data between applications.

5. Better Decision Making

Providers have access to complete patient information, enabling informed clinical decisions.

Real-World Example

Imagine a physician orders a blood test.

Without HL7:

• Staff manually enter information into multiple systems.
• Errors are more likely.
• Results may be delayed.

With HL7:

• The order is automatically sent to the laboratory system.
• Results are returned electronically.
• The physician receives updates immediately.

The entire workflow becomes faster, safer, and more efficient.

HL7 and Interoperability

One of the biggest challenges in healthcare is interoperability — the ability of different systems to work together.

HL7 plays a critical role in solving this problem by providing a common framework for data exchange.

Today, millions of HL7 messages are exchanged every day between hospitals, clinics, laboratories, pharmacies, and insurance providers worldwide.

Is HL7 Still Relevant Today?

Absolutely.

While newer standards such as FHIR are gaining popularity, HL7 Version 2 remains one of the most widely implemented healthcare messaging standards globally.

Many healthcare organizations continue to rely on HL7 for:

• Patient registration
• Laboratory integrations
• Radiology workflows
• Pharmacy communications
• Billing processes

As healthcare systems evolve, HL7 remains a foundational technology in healthcare interoperability.

Final Thoughts

Healthcare organizations depend on accurate and timely information exchange. HL7 provides the standard framework that allows diverse healthcare systems to communicate effectively.

By improving interoperability, reducing errors, and streamlining workflows, HL7 helps healthcare providers deliver better patient care and operate more efficiently.

One Standard. Many Systems. Better Healthcare.