The HL7 standards are at the nucleus of how your systems communicate with each other. Are you participating in a health system, HIE, digital health platform, or even an eCommerce-style marketplace in healthcare? Then you know firsthand how the problem of data silos affects you each and every day. Orders get stuck in limbo. Lab results take forever. Revenue cycle management crawls. The patient experience suffers.
Meanwhile, the force of regulators and payers is continually increasing. The 21st Century Cures Act increased the anticipation of interoperability in the US. It is reported by the ONC that close to 96 percent of US hospitals support certified EHR technology; however, the lack of real-time interoperability remains in the US markets. The standards of HL7 are inside nearly all of these systems, but usually not to their fullest capability.
This breakdown explains what the acronym “HL7” represents, the types of HL7 there are, the reason why the healthcare system involving the acronym “HL7” remains relevant in America in healthcare data transfer today, and the limitations one has to work within when dealing with the acronym “HL7” within the field of healthcare in the United States.
What Is HL7
“HL7” stands for Health Level Seven, and it’s a set of healthcare interoperability standards developed by Health Level Seven International, a nonprofit organization known as Health Level Seven International, or Health Level Seven International for short.
To explain, health information standards such as HL7 provide you with a universal language that can be understood when talking in messages between your EHRs and lab applications, radiology applications, pharmacies, billing applications, population health applications, and more. Before these standards were created, each project required custom programming.
Three factors characterize HL7 in healthcare in its day-to-day operations:
- Message structure: HL7 defines the use of segments, elements, and data types. The structure of a message used to convey the occurrence of the ADT event (admit, discharge, transfer) would conform to a certain standard that each compliant system would be able to interpret.
- Trigger events: HL7 relates its messages to trigger events, which can include new patient registration, ordering, or postings of results.
- Workflow Context: The HL7 specifications are capable of handling the entire range of healthcare workflows from ordering to results to billing.
The US has been utilizing HL7 v2 messaging in its hospital and provider workflows for many years. According to HIMSS survey results, more than 95 percent of large hospitals are utilizing HL7 v2 within their environment for point-to-point communications. That is why you may still require know-how related to HL7 despite adoption in FHIR.
Types of HL7 Standards
HL7 healthcare doesn’t come in a solitary form. Rather, it consists of a series of related standards, each designed for a given purpose and for a different time and technology. It is necessary to have knowledge about the broad categories to make good architectural decisions.
HL7 Version 2 (v2)
The most prevalent standard in EMR messaging in US hospitals as well as ambulatory centers isHL7 v2. The standard employs delimiting messages in text format with characters such as pipes and carets.
Examples of common HL7 v2 messages include:
- ADT messages for admissions, discharges, transferrals, and demographics.
- Messages regarding orders and results using ORM/ORU.
- SU messages for scheduling and appointments.
- DFT messages related to detailed financial transactions.
It is quite flexible and in widespread use. This flexibility can be a virtue as well as a problem since each vendor supports a slightly different set of local variations. Often, it is a matter of differences between vendors in the details of their HL7.
HL7 Version 3 (v3)
With HL7 v3, a more formal approach modeled using XML was included. The implementation was meant for greater semantic detail with a Reference Information Model. Though v3 inspired all others, its usage within US provider environments remained small compared with v2.
Yet, you can still observe the concept of “version 3″ in certain national schemes, as well as within the use cases for healthcare, but it is less prominent within the internal health data exchange for hospitals within version 2″.
Clinical Document Architecture (CDA)
CDA is an HL7 v3-based standard that details messaging for clinical documents, such as discharge summaries or consult documents. The Consolidated CDA (C-CDA) templates, which were mandated as part of Meaningful Use, more recently by the Cures Act, specify the formats of the summary of care documents.
According to ONC, as of 2021, “approximately 70 percent of non-federal hospitals within the United States were able to electronically transmit summary of care documents outside their organization,” commonly through the use of C-CDA based on Direct transports. C-CDA documents produced as part of the Office of the National Coordinator’s (ONC) meaningful use initiative are the “direct result of HL7 standards
Fast Healthcare Interoperability Resources (FHIR)
HL7 FHIR is the modern web-friendly standard from HL7 International. It uses REST APIs, JSON or XML, and a modular resource approach. FHIR is key for many recent healthcare data exchange initiatives in the US, such as patient access APIs and payer-to-payer exchange under CMS rules.
Key characteristics of FHIR include:
- Terminate resources for core entities like Patient, Encounter, Observation, Medication, and Claim.
- RESTful APIs that follow common guidelines in software engineering.
- Profiles that constrain resources for particular programs, for example, US Core profiles.
The ONC estimates, “About 87 percent of certified health IT developers support FHIR-based APIs, and support among the large EHR vendors is nearly universal.” Even with that momentum, HL7 v2 still carries much of the transactional messaging inside hospitals.
Why HL7 Still Matters
It is hard to overlook the importance of FHIR, so you may wonder where HL7 v2 and CDA fit. The fact is, HL7 healthcare standards are at the heart of healthcare information exchange systems in the US today. You still need them for four reasons.
1. HL7 Underpins Mission-Critical Workflows
The ADT messages trigger the creation of accounts, the management of the beds, the notification messages, and the capture of the charges. The messages for the orders and results for the lab initiate the diagnostic process. The scheduling messages are used to inform the call centers and portals. The revenue cycle teams use the HL7 information to reconcile activities and charges.
When you don’t send HL7 messages, patient flow will decrease, and the risk of losing revenue is high. When integrating HL7, it shouldn’t be an issue running in the background of IT for the organization, as it has become part of their daily tasks.
2. FHIR and HL7 v2 Coexist
FHIR opens up possibilities for you, particularly regarding patient- and partner-facing APIs, but you do not replace HL7 v2 overnight. You find yourself sitting in front of bridging HL7 v2 feeds coming directly from source systems into a FHIR layer for accessing external applications. This willHur maintains legacy business workflows while you enhance how you access them.
Misaligned expectations emerge when teams use FHIR as a replacement for traditional EMR messaging standards instead of a complement to these standards. A conservative integration plan takes into consideration what you already have in terms of the HL7 portfolio.
3. Regulatory and Program Alignment
Currently, some US systems still have these two mechanisms for compliance, namely C-CDA and HL7 v2. Most HIEs store the data collected via HL7 v2 and/or C-CDA, which is presented via FHIR-based APIs/portal views.
The Office of Inspector General mentioned some instances of information blocking involving providers who failed to provide reasonable electronic access. The HL7 global network of healthcare infrastructure makes it less risky for providers to follow HL7 standards.
4. Scale and Installed Base
The healthcare system in the US has been engaging in the use of HL7-driven integration efforts for a long time. In fact, large healthcare institutions tend to manage thousands of HL7 interfaces. The whole infrastructure cannot be replaced in the short term.
Rather, you can extract more value from standardizing and managing HL7 data exchange with a platform layer of FHIR analytics on top. In doing so, you will realize short-term gains without disrupting working processes.
Limitations
Although HL7 standards of healthcare exist, they do not offer all the answers regarding interoperability. The need to understand the boundaries of HL7 standards for a sustainable data strategy will be explained below.
1. Variability Across Vendors
HL7 v2 supports many optional segments, or so-called Z segments. These are often determined by vendors as well as health systems. Two ADT messages from two different hospitals are never the same, even if the two are both HL7 v2 compliant.
This adds to the amount of work involved in interface mapping and testing activities. A report by KLAS on interoperability shows that less than 40% of the providers believe cross-vendor interoperability to be mature. This is attributed to the variations that exist in the implementation of HL7.
2. Limited Semantic Consistency
Structure is more defined in the definition of an HL7 message than the meaning. You’ll still have semantics issues without standardized code or terminology, like a lab in LOINC and problems in SNOMED-CT. A system and a legacy system could represent the same thing in a different way.
This hinders analytics programs and population health programs that rely on clean data.
3. Complex Management at Scale
Hundreds or thousands of point-to-point interfaces for HL7 support can be a risk. Each new interface has to be mapped, tested, monitored, and controlled for change. Your EHR system makes a change, or a third-party system makes a change, and the interfaces require validation.
Lack of good interface governance is a factor in downtime and hidden operational costs. The Ponemon Institute placed the cost of system downtime to hospitals at 8,662 dollars a minute if the downtime affects clinical operations. Fragile integration layers are contributing factors in some of these downtimes.
4. Gaps for Modern Use Cases
HL7 v2 is not built for mobile applications, consumer-centric experiences, or event-driven cloud systems. It can be interfaced with those design patterns, but this becomes more complex. FHIR is more suited to those design patterns.
Smart architecture directs the right use cases to FHIR interfaces and the right business flows to HL7 v2 interfaces. API gateways, integration engines, and managed exchanges are used to keep both of these in sync.
Conclusion
HL7 healthcare standards are not a legacy problem to retire. They represent a living foundation for healthcare data exchange in the US. You rely on HL7 v2 for admissions, orders, results, billing, and many other core workflows. You use CDA for clinical summaries. You use FHIR for modern APIs and regulatory access requirements.
It’s not which one you choose: HL7 v2, CDA, and FHIR. It’s how to coordinate them so your teams see consistent, timely information in every workflow. This requires a strategy that weaves together HL7 data exchange, healthcare interoperability standards, and EMR messaging standards into one cohesive integration fabric.
That integration fabric should give you:
- Reliable HL7 interfaces with strong monitoring and alerting.
- Normalized data models that reduce vendor-specific variations.
- FHIR APIs for curated data sets for partners and innovators.
- Clear ownership across IT, clinical, and revenue cycle stakeholders.
When you get to that point, HL7 healthcare becomes a force multiplier to clinical quality, patient experience, and financial performance-not a barrier.
