Lab Analyzer Integration Explained: HL7, ASTM and LIS Interfacing

In many labs, results still travel from the analyzer to the report by hand: someone reads a printout or screen and types the values into the lab software. It works, but it is slow, and every typed value is a chance for a transcription error.

Analyzer integration (often called LIS interfacing) removes that step. The analyzer sends results straight to your laboratory information system (LIS), matched to the right sample. This guide explains how that connection works, in plain language.

The two jobs of an analyzer interface

Every interface has to solve two problems:

1. Getting bytes from the analyzer to the computer reliably — the physical connection and the low-level protocol.
2. Understanding what those bytes mean — which patient, which sample, which test, which result, which flag.

Different standards handle each job.

Physical connection: RS232 or TCP/IP

• RS232 serial is a direct cable from the analyzer’s serial port to a computer. It is common on long-serving instruments and many benchtop analyzers.
• TCP/IP uses the lab’s network. Newer analyzers usually connect this way, and one computer can talk to several analyzers over the network.

A good interface supports both, so you don’t have to replace instruments to integrate them.

ASTM: the classic laboratory protocol

Most analyzers that don’t speak HL7 use the ASTM family of standards, now maintained by CLSI:

• LIS01-A (formerly ASTM E1381) handles the low-level transfer. The analyzer starts with an ENQ, the receiver answers ACK, data is sent in numbered frames with checksums, and the session ends with EOT. If a frame is corrupted, it is re-sent.
• ASTM E1394 (LIS2-A2) defines what the data means. A message is made of records, each starting with a letter:

Record	Meaning
H	Header — which instrument is sending
P	Patient information
O	Order — the sample ID and tests requested
R	Result — test code, value, units, reference range and flag
C	Comment
L	Terminator — end of message

A single complete blood count might arrive as one H, P and O record followed by twenty or more R records.

HL7 v2: the hospital messaging standard

Some analyzers, and most hospital systems, use HL7 version 2 (v2.3.1 is a widely used version). An HL7 message is made of segments separated by line breaks:

• MSH — message header (who sent it, message type)
• PID — patient identification
• OBR — the order or request
• OBX — each individual observation, such as a result value

Result messages are typically of type ORU^R01; order messages of type ORM^O01. Over a network, HL7 is usually wrapped in a simple framing protocol called MLLP.

Uni-directional vs bi-directional

• Uni-directional: the analyzer only sends results. Tests are still selected on the analyzer itself.
• Bi-directional: the LIS also sends orders to the analyzer. When a barcoded sample is loaded, the analyzer asks for (or is sent) the tests ordered for that barcode and runs only those. This saves time and prevents wrong or missed tests.

Bi-directional interfacing needs barcoded sample tubes, which most labs adopt anyway for sample tracking.

Beyond numbers: histograms and scattergrams

Hematology analyzers also produce RBC, PLT and WBC histograms and differential scattergrams. Good integrations capture these graphs and attach them to the patient report, so the pathologist and doctor see the full picture, not just the numbers.

Why barcode matching matters

The single most important safety feature of any integration is that every result is tied to its sample barcode. That is what guarantees the right value reaches the right patient, even when several analyzers are running at once.

What to check before you connect an analyzer

1. Which protocol does it support? ASTM or HL7, and which version. This is in the analyzer’s interface or host communication manual.
2. Which port? RS232 or Ethernet, and the communication settings (baud rate, IP and port).
3. Uni- or bi-directional? And whether the analyzer queries the host per sample or expects a batch of orders.
4. Test code mapping. The analyzer’s test codes must be mapped to the tests in your LIS.
5. What happens when the network or LIS is down? Results should be queued and delivered later, never lost.
6. Is there an audit log? When a value is questioned, you need a record of exactly what the analyzer sent.

The result

A well-integrated lab removes typing from the result path altogether. Results arrive within seconds of the analyzer finishing, flags and graphs come with them, and staff time goes into verification instead of data entry.