Quick facts
- The erythrocyte sedimentation rate is measured by letting red cells fall in a column of blood and reading how far they travel in a set time.
- United States: the tube and the test share one entry. 21 CFR 864.6700 covers an erythrocyte sedimentation rate test and places it in Class I.
- United States: the instrument that reads the result automatically sits in a different entry. 21 CFR 864.5800 covers an automated sedimentation rate device and also places it in Class I.
- Canada: a sedimentation tube is a non-invasive device and falls to Class I under Rule 7(1) of Schedule 1 to the Medical Devices Regulations, SOR-98-282.
- Canada: an automated analyser is an active device that does not meet the imaging or energy rules, so Rule 12 classifies it as Class I.
- The purchase question is the tube, the rack and the reader as one timed system, not three unrelated items.
An ESR is a timed measurement, and the timing is the test. A tube that is not upright, a rack that leans, or a reader with a different reading window will change the result before any clinical interpretation begins. That is why the two lines, the manual tube and the automated analyser, sit so close together in the device rules and so far apart in practice. This article sets out what the test measures, how each country files the tube and the instrument, and what a laboratory should confirm before it reorders.
What does an erythrocyte sedimentation rate test measure?
A blood sample is drawn into a tube that contains an anticoagulant, stood upright in a rack, and left for a fixed time. The red cells settle, and the distance they fall is read. 21 CFR 864.6700 describes an erythrocyte sedimentation rate test as a device that measures the length of time required for the red cells in a blood sample to fall a specified distance, or a device that measures the degree of sedimentation taking place in a given length of time.
Three properties decide whether the measurement holds together:
- The tube and its bore. The internal diameter and the graduation set the reading scale.
- The rack and the vertical. A tube that is not plumb settles differently.
- The reading method. A reader can be a manual scale or an instrument that measures automatically, and the two are separate entries in the United States.
The last point is the one that turns an ESR order into a system order. 21 CFR 864.5800 describes an automated sedimentation rate device as an instrument that measures automatically the erythrocyte sedimentation rate in whole blood, which makes it a distinct article from the tube it reads.
How do the Canadian and United States rules classify ESR lines?
The United States uses two named Class I entries, one for the tube and test and one for the automated instrument. Canada reaches the same class by rule.
| Item | Canada | United States |
|---|---|---|
| Entry that catches the tube | None; class derived by rule | 21 CFR 864.6700, erythrocyte sedimentation rate test, Class I |
| Entry that catches the analyser | None; class derived by rule | 21 CFR 864.5800, automated sedimentation rate device, Class I |
| What drives the class of the tube | Non-invasive device under Rule 7(1) | The device definition itself |
| What drives the class of the analyser | Active device not caught by another rule, Rule 12 | The device definition itself |
| Calibrator or quality control support | Rule 7(2)(a), Class II | Named products handled through the general provisions of the part |
| Premarket position | Licence only where the derived class requires one | Exempt from premarket notification, subject to 21 CFR 864.9 |
| Wording that decides the case | Non-invasive; and for the analyser, any other active device | Measures the degree of sedimentation; measures automatically |
Two clauses do the work in Canada. Rule 7(1) of Schedule 1 sends all other non-invasive devices to Class I, and a tube that holds blood for measurement is non-invasive. It is worth noting what does not apply: Rule 5 lifts a non-invasive device to Class II only when it is intended for channelling or storing gases, liquids, tissues or body fluids for the purpose of introduction into the body. A sedimentation tube stores a specimen for measurement, not for introduction, so Rule 5 does not reach it and the tube stays at Rule 7(1).
The analyser is handled by a different rule because it is active. Rule 12 states that any other active device is classified as Class I. An automated ESR instrument does not emit ionizing radiation, does not administer or withdraw energy to or from the body, and does not image or monitor a physiological process in the sense Rule 10 uses, so it falls to Rule 12 and stays at Class I. That is the same class the United States gives it, reached by a different route.
Which ESR methods use which lines?
| Method | Device | What it uses | Class note |
|---|---|---|---|
| Manual Westergren | Graduated tube and rack | A fixed bore and a set reading time | Class I tube; US entry 864.6700; Canada Rule 7(1) |
| Modified Westergren | Sealed tube and rack | The same reading scale in a closed tube | Class I; confirm the reading window with the reader |
| Automated analyser | Instrument with its own reader | Reads the fall automatically | Class I; US entry 864.5800; Canada Rule 12 |
| Quality control material | Reference or control sample | Checks the reading against a known value | Rule 7(2)(a) can move this to Class II in Canada |
The method view matters at the point of order. A laboratory that runs a manual tube and later adds an analyser has added a device with its own entry in the United States and its own place in the equipment file, and the two reading methods should be compared before both are relied on.
Does a calibration or quality control material change the class?
The device class of the tube and the analyser does not change, but the language a supplier uses can change the class of a related article. In Canada, Rule 7(2)(a) classifies a device as Class II when it is intended to act as a calibrator, tester or quality control support to another medical device. A reference tube or control sold as a verification aid for the analyser is the kind of article that clause reaches, which is why the wording on the label and the catalogue line is worth reading before the class is assumed.
Four consequences follow for a laboratory:
- The tube and the reader are one system. Buy the rack and the reading method as a pair.
- The vertical is part of the method. The rack design and the bench level belong in the method file.
- A reference tube is not a specimen tube. Keep the verification line labelled as such.
- The record belongs with the method. The reading time, the reader and the control result belong together in the method file.
Which consumables does a specimen bench go through?
A specimen bench restocks tubes, containers, pipettes, gloves, disinfectant and waste bags in the same cycle. For laboratories buying at case level, the wholesale ordering page sets out account and case terms, and the B2B wholesale collection lists the lines held for institutional buyers. The sterile 15 mL centrifuge tube, 500 per case is the kind of line we hold for bench work, and laboratories that also run an in-house sterilizer can start with the biological indicator 5-pack trial and read the sterilization monitoring collection for the monitoring lines.
Sources
- 21 CFR 864.6700, erythrocyte sedimentation rate test
- 21 CFR 864.5800, automated sedimentation rate device
- Medical Devices Regulations, SOR/98-282, full text, Schedule 1
- Health Canada, medical devices
- ISO 15189:2022, medical laboratories, requirements for quality and competence
- ISO 6710:2017, single-use containers for venous blood specimen collection
- Public Health Ontario, laboratory test information index
- Public Health Ontario, infectious diseases
- Clinical and Laboratory Standards Institute
- Institute for Quality Management in Healthcare
- College of Medical Laboratory Technologists of Ontario
- Ontario, Laboratory and Specimen Collection Centre Licensing Act
- Canadian Centre for Occupational Health and Safety, OSH answers
- CCOHS, personal protective equipment
- World Health Organization, laboratory biosafety manual
- openFDA device classification database
- FDA device classification database search
- FDA CLIA waived analytes database
- US OSHA bloodborne pathogens standard, 1910.1030
- World Health Organization, oral health fact sheet
Related reading
- Capillary Tubes in Canada vs the US: Which Size and Standard Should a Lab Specify
- Microcentrifuge Tubes in Canada vs the US: Which Standards and Labelling Apply
- Serological Pipettes in Canada vs the US: Which Class and Colour Code Apply
- Laboratory Glassware in Canada vs the US: Which Standards Apply
CliniEco Medical supplies laboratory and clinic consumables of the kind described in this article. MDEL #35334. This article is written for laboratory, procurement and quality professionals and is not clinical or accreditation guidance; method validation and result interpretation belong to the laboratory director.
Frequently Asked Questions
Is an ESR tube a medical device in the United States?
Yes. 21 CFR 864.6700 covers an erythrocyte sedimentation rate test, which includes the tube that holds the sample during the timed measurement, and places it in Class I.
What class is an automated ESR analyser in the United States?
It is Class I, and it has its own entry rather than sharing the tube's. 21 CFR 864.5800 covers an automated sedimentation rate device that measures the erythrocyte sedimentation rate in whole blood automatically.
How is an ESR tube classified in Canada?
It is a non-invasive device and falls to Class I under Rule 7(1) of Schedule 1 to the Medical Devices Regulations. Rule 5 does not lift it, because that rule applies only to a container intended to channel or store fluids for introduction into the body, not to a specimen held for measurement.
How is an automated ESR analyser classified in Canada?
As an active device, it is classified under Rule 12, which states that any other active device is Class I. It does not emit ionizing radiation and does not image or monitor a physiological process in the sense Rule 10 uses, so it stays at Class I, the same class the United States gives it.
Can an ESR product be Class II in Canada?
A quality control or reference material sold as a calibrator, tester or quality control support to another medical device can be, because Rule 7(2)(a) classifies such a device as Class II. The working tube and the analyser remain Class I.
What should a laboratory keep on file for ESR lines?
The tube bore and the rack, the reading method and window of the analyser, the comparison of the manual and automated methods where both are used, and the control result for any reference material. The reading time and the reader belong together in the method file.
Is an ESR result a waived test in the United States?
The device class and the test complexity are different questions. The tube and the analyser are Class I devices, while the complexity of the test that uses them is set in the CLIA regulations and can be checked against the FDA waived-analytes database. A laboratory should confirm its certificate category before it reports the result.
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