Written by Technical Team | Last updated 17.07.2025 | 9 minute read
For healthtech innovators looking to scale within the UK healthcare ecosystem, integrating with existing Electronic Patient Record (EPR) systems is often a necessary and technically complex step. Among the leading EPR solutions adopted by NHS Trusts is System C’s CareFlow EPR, a robust, comprehensive platform underpinning clinical, administrative, and operational workflows in many acute and community settings.
This article explores the practical and technical considerations involved in System C integration, providing guidance for digital health developers, engineers, and integration leads. Whether you’re working on a patient-facing application, clinical decision support tool, or a backend analytics solution, understanding how to integrate with CareFlow EPR is key to ensuring your solution can interoperate securely and effectively within NHS infrastructure.
System C is one of the UK’s primary suppliers of integrated EPR solutions. Their flagship product, CareFlow EPR, is a modular suite covering Patient Administration (PAS), Order Communications (OCS), Electronic Prescribing and Medicines Administration (EPMA), Maternity, and Clinical Documentation. It serves as a central source of truth for patient records and drives many of the day-to-day operations within NHS Trusts.
CareFlow EPR is designed with interoperability in mind and supports Health Level 7 (HL7 v2.x) messaging standards. The platform integrates with Trust Integration Engines (TIEs) via the CareFlow Integration Engine (CIE) – a middleware layer that acts as the communication bridge between CareFlow EPR and third-party systems.
At the heart of a successful System C integration project lies a deep understanding of the message types and flows supported by the CareFlow EPR platform. The system supports both inbound and outbound HL7 messages, enabling third-party solutions to either publish data to, or consume data from, the EPR.
The supported interface types include Master Patient Index (MPI) feeds, inpatient admission and discharge notifications, waiting list management, outpatient referrals and appointments, casualty activity, contact management, master file maintenance, and order/result messaging for both general clinical and laboratory domains.
For most digital health vendors, the most relevant messages are outbound ADT (Admit Discharge Transfer) messages and inbound orders and observations (OMG/ORU or OML/OUL message types). These allow you to track patient movement, observe clinical milestones, and submit diagnostic or procedural orders directly into the clinical workflow.
System C’s architecture mandates that third-party systems connect to the CareFlow Integration Engine over TCP/IP sockets, using Minimal Lower Layer Protocol (MLLP) framing. All data is encoded in UTF-8, with strict sequencing and guaranteed delivery mechanisms enforced through ACK (Acknowledgement) messages. This provides a reliable, FIFO-queued message exchange with transactional integrity.
CareFlow IE is typically deployed with up to five TCP servers, each listening for different types of message interactions. For outbound feeds, your system will connect to receive messages via a designated port. For inbound submissions (e.g. placing orders or registering patients), you’ll connect to a separate listener configured for the relevant message type.
In some cases – such as integrating with Maternity modules or receiving real-time ED alerts – synchronous application acknowledgements may be required, necessitating robust request-response handling and error management capabilities within your integration layer.
While CareFlow EPR adheres broadly to HL7 UK v2 standards (version A.2), it introduces a number of extensions and conventions which third-party integrators must accommodate.
For example, null vs. empty value handling is crucial. The EPR differentiates between omitted fields (implying no update) and explicit nulls (“”) which denote data deletion. This affects patient demographics, identifiers, and clinical fields such as allergies and next of kin.
Message segments are strict and conform to a predefined structure. The PID segment, for instance, supports multiple identifier types (e.g., HOSP for hospital number, NHS for national identifier) with a prescribed ordering and conditional rules depending on the message direction and type.
Similarly, the EVN, MSH, and PV1 segments have context-sensitive interpretations, particularly when dealing with home leave, bed transfers, or medically fit status updates. Developers should carefully validate each segment and subfield using the System C specification before assuming HL7 interoperability.
CareFlow EPR is highly configurable and often tailored to individual Trust deployments using a plug-in architecture. This means that two Trusts running the same version of CareFlow EPR might have different workflows, segment populations, and message triggers.
From an integration standpoint, this presents both a challenge and an opportunity. On one hand, you’ll need to work closely with the Trust’s integration team to confirm which plug-ins are active (e.g., Medically Fit plugin v2, Waiting List v2) and how they affect message content. On the other hand, this flexibility means your solution can target specific workflows or clinical use cases, providing differentiated value.
Certain custom segments (e.g., ZU1, ZU3, and ZU4) are used to convey UK-specific fields such as RTT pathways, overseas charging status, and waiting list comments. You’ll need to ensure your parser or message builder can handle these gracefully, especially if your application is parsing inbound ADT or ORU messages.
Like all integrations in NHS infrastructure, data governance is paramount. System C EPR contains patient-identifiable information (PII) and sensitive clinical data, so your integration must be compliant with NHS DSPT, DCB0129/0160 standards, and local IG protocols.
You must also ensure that transport security is implemented appropriately. While the core MLLP protocol operates over TCP sockets without inherent encryption, most Trusts will require VPNs or IPsec tunnels between your system and the CareFlow IE instance. Message-level security (e.g., digital signatures, data masking) may also be mandated, depending on the data you are handling.
It’s critical to also build robust error handling and retry mechanisms. Failed HL7 messages, malformed segments, or sequence errors can cause cascading issues, so your integration should be able to capture and log these occurrences and support replay or reconciliation where appropriate.
A successful System C integration begins long before the first message is exchanged. It requires early engagement with the Trust’s integration and IT teams, clear documentation of message requirements, and a shared understanding of use cases.
Start by reviewing the System C HL7 Message Specification in its entirety. Identify which message types align with your product’s functionality and confirm with the Trust which messages are enabled. Request message samples, segment population rules, and details on plug-in configurations. Ensure that your development and QA environments can simulate inbound and outbound message flows under realistic scenarios.
Where possible, use a dedicated integration test environment provided by the Trust or their LSP (Local Service Provider). Validate message formatting, segment completeness, and data accuracy end-to-end. Tools such as HL7 simulators, Wireshark (for TCP traffic), and message validation engines will prove invaluable during this phase.
System C’s integration architecture is aligned with broader NHS initiatives around interoperability, data sharing, and open APIs. While HL7 v2 remains the workhorse for transactional messaging, Trusts are increasingly exploring FHIR-based APIs for newer applications, especially in contexts like patient access, population health, and care coordination.
System C has signalled future support for FHIR endpoints via its CareFlow Connect platform and is involved in NHS England’s interoperability programmes. However, for most production-critical integrations today, HL7 v2 remains the required and supported standard.
If you are building a solution that needs to consume or emit clinical data in real time – such as notifying clinicians of results, managing appointments, or updating a shared care plan – then working within the HL7 v2 and System C IE model remains essential. It’s the lingua franca of NHS integration today, and mastering it is the fastest route to scale your digital health innovation.
Integrating with System C’s CareFlow EPR is both a technical and collaborative exercise. While the platform offers robust support for HL7-based interoperability, each integration must be tailored to the workflows, configurations, and security requirements of the host Trust.
For digital health companies, understanding the specifics of System C integration – from message structures and connectivity protocols to deployment nuances and governance frameworks – is a critical enabler of commercial and clinical success.
With the right preparation, technical alignment, and ongoing collaboration, integrating with CareFlow EPR can unlock deep, real-time access to the patient and operational data needed to power transformative healthcare solutions.
What technologies are commonly used alongside System C integration for analytics and reporting?
System C CareFlow EPR integrations often feed data into Business Intelligence tools like Power BI, Tableau, or QlikView via ETL processes. Many Trusts also use intermediate data layers or data lakes built on SQL Server, Azure, or Snowflake to manage and visualise aggregated patient data for clinical and operational insights.
Can System C CareFlow EPR integrate with mobile health apps?
While System C’s HL7 messaging is primarily used for system-to-system integration, mobile apps can connect indirectly via middleware or APIs layered on top of the Trust Integration Engine. For example, mobile platforms may access patient data through a FHIR proxy, local API gateway, or integration microservices built by the Trust or their partners.
Is System C integration compatible with cloud-based digital health solutions?
Yes, many NHS Trusts now allow hybrid or cloud-native vendors to integrate with on-premise CareFlow systems. This typically requires secure network access via VPN or HSCN, data residency compliance, and alignment with the Trust’s IG and DSPT standards. However, cloud deployments must not initiate direct socket connections without NHS oversight.
Does System C offer a FHIR API for integration?
System C has been developing FHIR capabilities, particularly through its CareFlow Connect platform. While HL7 v2 remains the primary integration mechanism, FHIR APIs may be available for selected use cases like care coordination, encounter history, and patient summaries – depending on the Trust’s configuration and product roadmap.
How long does a typical System C integration project take to go live?
Project duration varies but typically spans 6 to 12 weeks from scoping to deployment. Timelines depend on the integration complexity, message types required, and the responsiveness of the Trust’s technical teams. Early engagement and clear documentation can significantly reduce project lead times.
Can third-party vendors write data directly into CareFlow EPR?
Direct write access to CareFlow EPR is highly restricted due to clinical safety and governance. Most integrations are read-only, especially for new vendors. Writing data into the EPR (e.g. referrals or test results) often requires extensive validation, clinical safety cases (DCB0129/0160), and close collaboration with System C and the host Trust.
Is it possible to simulate System C message flows without a live NHS environment?
Yes. Many integrators create test harnesses using open-source HL7 tools (like Mirth Connect or HL7 Soup) to simulate CareFlow message flows. System C can also provide message samples and mock MLLP endpoints during pre-integration testing, although availability varies across Trusts.
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