Quick facts
- A platelet aggregometer measures how platelets clump when an agonist is added, the test behind platelet-function assessment.
- In the United States it files under 21 CFR 864.6675, Platelet aggregometer, at Class II, with product codes JBX, GKW and JBY.
- Canada regulates it as an in vitro diagnostic device under Part 2 of Schedule 1, used in diagnosis and patient management.
- Part 2 Rule 4 sets an IVDD used in diagnosis or patient management at Class II, unless one of its listed higher-risk categories applies.
- The instrument and the agonist reagents are separate devices; the class of each follows Part 2 Rule 7, which takes the higher-risk of the two.
- Entries, classes and product codes below were checked against the eCFR, the Regulations and the openFDA classification database on 2026-10-13.
A platelet aggregometer measures how readily platelets clump when an agonist is added to a plasma sample, which is how a laboratory assesses platelet function and monitors antiplatelet therapy. A haemostasis service buys the instrument as capital equipment and runs it with a stream of agonists and cuvettes. It is Class II in the United States under a named regulation number, and Class II in Canada as an in vitro diagnostic device used in diagnosis. This article sets out both routes and the consumables the test consumes, alongside the evacuated blood collection tubes that start the specimen chain.
What is a platelet aggregometer?
The instrument warms a sample of platelet-rich plasma, adds an agonist that should make the platelets clump, and records how the light transmission through the sample changes as the clumps form. The curve that results — its slope, its peak and whether it reverses — is the aggregation trace the clinician reads.
Two forms share the description. A light-transmission aggregometer reads the change in turbidity of a stirred sample; an impedance aggregometer reads the change in electrical resistance across electrodes as platelets settle on them. Both are platelet aggregometers under the same regulation number, and both consume agonists, cuvettes and a specimen collection set.
What class is it in the United States?
It is Class II. 21 CFR 864.6675 is titled Platelet aggregometer, and the openFDA device classification API lists product codes JBX (Aggregometer, Platelet), GKW (Aggregometer, Platelet, Thrombokinetogram) and JBY (Aggregometer, Platelet, Photo-Optical Scanning) under that regulation number. A Class II device of this kind reaches the market through the premarket notification route.
The regulation is written around the measurement, not the detection method. A light-transmission instrument and an impedance instrument are described by the same number, which is why a laboratory comparing two aggregometers is comparing formats, not classes.
| Item | Detail |
|---|---|
| US regulation | 21 CFR 864.6675 - Platelet aggregometer |
| US class | Class II |
| Product codes | JBX, GKW, JBY |
| Route to market | Premarket notification before commercial distribution |
| Applied part | Measures a plasma sample in a cuvette; no contact with the patient |
How does Canada classify a platelet aggregometer?
Canada regulates the instrument as an in vitro diagnostic device. Because aggregation testing is used in the diagnosis and management of a patient's condition, Part 2 Rule 4 of Schedule 1 applies: "An IVDD that is not subject to rules 1 to 3 and that is intended to be used in diagnosis or patient management is classified as Class II, unless it falls into one of the following categories, in which case it is classified as Class III." The listed categories are cancer screening or diagnosis, genetic testing, congenital-disorder screening in a fetus, a risk that an erroneous diagnostic result would cause death or severe disability, disease staging, and the monitoring of drugs or biological components where an erroneous result risks an imminent life-threatening situation.
For a routine platelet-function instrument none of those higher-risk categories is met, so the Class II default of Rule 4 stands. Where the same instrument is used to monitor a drug whose erroneous result would put the patient in imminent danger, the Class III limb can be engaged, and the intended use on the labelling is what decides between the two.
| Item | Canada | United States |
|---|---|---|
| Named entry | None; IVDD classified by rule | 864.6675, Class II |
| Class | Class II (Part 2 Rule 4) | Class II |
| Governing text | Schedule 1, Part 2, Rule 4 | 21 CFR 864.6675 |
| Regime | In vitro diagnostic device | Medical device |
| Could it be Class III? | Only if a listed higher-risk category is met | Handled inside the Class II regulation |
Do Canada and the United States reach the same answer?
They do, and here the reasoning is closer than it was for a separating centrifuge. Both systems treat platelet-function testing as a mid-risk activity: the United States names the instrument and fixes it at Class II, and Canada reaches Class II through the IVDD rule for diagnosis and patient management. The shared answer reflects a shared judgement about the risk of the test.
Where the two can part is at the edges. An instrument marketed to monitor a high-risk drug, or one bound to a genetic or cancer-related assay, can reach Class III on the Canadian side while the instrument regulation stays at Class II on the American side. The binding rule is Part 2 Rule 7: an instrument and the assay it runs take the class of the higher-risk device.
The other edge is the specimen. Aggregation testing starts with a blood draw, and the collection set the instrument's instructions specify is part of the test's validity, not a general-purpose consumable. A laboratory that changes the collection tube without checking the assay's instructions has changed a variable the instrument cannot detect, which is why the specimen set is listed alongside the agonist on the same order.
None of this moves the class. The instrument stays at Class II in both countries, and the reagents and the specimen set are separate devices whose own classes are set by their own intended uses. The classification question and the procurement question are related but separate, and a haemostasis service answers both before it places an order.
What should a haemostasis service check when ordering?
Three checks. First, confirm whether the instrument is light-transmission or impedance, because the agonist set and the cuvette are not interchangeable between the two. Second, confirm the agonist reagents are stocked as their own line, since they are separate devices and are consumed at a different rate from the instrument. Third, confirm the specimen collection set the assay specifies, because aggregation testing is sensitive to how the sample is drawn and held. The choice between a light-transmission and an impedance instrument is made on the reagent set and the sample volume, not on the class, since both are described by the same entry.
Haemostasis services also reorder the sample-handling consumables for the same bench. Clinics that stock for a whole practice can order through the wholesale programme and request a bulk quote for a standing or annual order; the graduated specimen container sits in the same catalogue. Reselling? become a distributor.
How does the class affect a haemostasis laboratory's routine?
The instrument's class sets how the analyser reaches the market; the laboratory's routine sets how a run is recorded. An aggregation run is logged with the agonist, the dose, the calibration and the specimen time, so a curve can be reviewed against the patient's earlier runs. The analyser follows the maker's maintenance schedule, and the agonists are held to their own storage conditions.
Because aggregation is time-sensitive, the record includes the draw time and the run time, which is what lets a reviewer see whether a flat curve reflects the patient or the specimen. The class does not set those fields; the laboratory's procedure does, and the record is the visible evidence that the procedure was followed.
Sources
- openFDA device classification API
- Medical Devices Regulations, SOR/98-282, full text and Schedule 1
- US FDA, medical device databases
- US FDA, overview of device regulation
- Health Canada, medical devices
- Health Canada, establishment licensing
- Clinical and Laboratory Standards Institute
- Public Health Ontario, infection prevention and control
- ISO 15189:2022, medical laboratories - requirements for quality and competence
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, application of risk management to medical devices
- US CDC, laboratory quality
- World Health Organization
- Standards Council of Canada
- CSA Group
- CCOHS, OSH answers
- ISO 15197:2013, in vitro diagnostic test systems
- Health Canada, in vitro diagnostic devices
- World Health Organization, laboratory quality
- Public Health Ontario, laboratory specimen collection
Printable record sheet. A haemostasis service records each aggregation run, and the printed sheet is the copy kept with the specimen record. Open the sterilization log sheet library — the downloadable pack holds a steam-cycle log, a reprocessing-room checklist and an equipment-maintenance sheet. No account and no sign-up; print as many copies as your log needs.
Log generator. The generator lays out the run and agonist columns so an analyser log is complete in one pass. Run the sterilization log generator to build a dated, facility-labelled cycle sheet you can print or file straight into your quality manual.
Ask a compliance specialist. Whether an aggregometer stays Class II or moves up turns on its intended use; a written answer keyed to your analyser and province settles it. Ask a compliance specialist — you get a written answer specific to your equipment and province, with the regulation or standard it is based on cited.
Related reading
- Coagulation analysers in Canada vs the US
- ESR tubes in Canada vs the US
- Blood collection tube systems in Canada vs the US
CliniEco Medical supplies eye care, laboratory and dental consumables of the kind described in this article. MDEL #35334. This article is written for optometry, laboratory and dental procurement professionals and is not legal advice; the class of a device and the records a practice keeps belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
What class is a platelet aggregometer in the United States?
Class II, under 21 CFR 864.6675, Platelet aggregometer, product codes JBX, GKW and JBY.
What class is it in Canada?
Class II, as an in vitro diagnostic device used in diagnosis or patient management, under Part 2 Rule 4 of Schedule 1.
Could it ever be a higher class in Canada?
Yes, if it is intended for a listed higher-risk use, such as monitoring a drug where an erroneous result would risk an imminent life-threatening situation.
Is the agonist a separate device?
Yes. The instrument and the agonist reagents are separate devices; under Part 2 Rule 7 each takes the class of the higher-risk device they are used together.
What else is a platelet aggregometer called?
It is also written as platelet function analyser, aggregometer, and impedance or light-transmission aggregometer.
Does the detection method change the class?
No. Light-transmission and impedance instruments are described by the same regulation number; the method changes the reagent set, not the class.
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