---
title: How to Apply MDR Classification Rule 10: Active Diagnostic Devices
description: MDR Annex VIII Rule 10 classifies active diagnostic and monitoring devices. Here is how to apply the IIa baseline and the IIb escalations.
authors: Tibor Zechmeister, Felix Lenhard
category: Device Classification & Conformity
primary_keyword: MDR Rule 10 active diagnostic devices
canonical_url: https://zechmeister-solutions.com/en/blog/mdr-rule-10-active-diagnostic
source: zechmeister-solutions.com
license: All rights reserved. Content may be cited with attribution and a link to the canonical URL.
---

# How to Apply MDR Classification Rule 10: Active Diagnostic Devices

*By Tibor Zechmeister (EU MDR Expert, Notified Body Lead Auditor) and Felix Lenhard.*

> **Rule 10 of Annex VIII to Regulation (EU) 2017/745 classifies active devices intended for diagnosis and monitoring. The baseline is Class IIa. The rule escalates to Class IIb when the device supplies energy absorbed by the body in a potentially hazardous way (excluding illumination in the visible spectrum), when it images in vivo distribution of radiopharmaceuticals, when it allows direct diagnosis or monitoring of vital physiological processes where variations could result in immediate danger, and when it emits ionising radiation for diagnostic or therapeutic interventional radiology. Classification under Rule 10 is governed by Article 51 of the MDR. The authoritative interpretation guide is MDCG 2021-24 (October 2021).**

**By Tibor Zechmeister and Felix Lenhard. Last updated 10 April 2026.**

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## TL;DR

- MDR Annex VIII Rule 10 assigns active diagnostic and monitoring devices to Class IIa by default, with four distinct escalation paths into Class IIb.
- The first escalation fires when the device supplies energy that will be absorbed by the human body in a potentially hazardous way, excluding illumination of the patient's body in the visible spectrum.
- The second escalation fires when the device images the in vivo distribution of radiopharmaceuticals.
- The third escalation fires when the device allows direct diagnosis or monitoring of vital physiological processes, with a further carve-out for variations of a parameter that could result in immediate danger to the patient.
- Active devices intended to emit ionising radiation and intended for diagnostic or therapeutic interventional radiology, including devices that control or monitor such devices, or directly influence their performance, are Class IIb under Rule 10.
- Rule 10 only covers active devices intended for diagnosis and monitoring. Active therapeutic devices fall under Rule 9. Standalone software is classified under Rule 11. MDCG 2021-24 (October 2021) contains worked examples and is the first cross-reference a Notified Body will check.

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## Why Rule 10 matters

Rule 10 is where most active diagnostic device founders land. Ultrasound imaging, electrocardiographs, patient monitors, pulse oximeters, capnographs, fundus cameras, MRI, CT, and nuclear medicine imaging all pass through Rule 10. The rule is compact but carries interpretive weight: the escalations depend on judgments about what "potentially hazardous" means, what counts as a "vital physiological process," and when a monitored variation creates "immediate danger."

A wrong Rule 10 call is expensive. Class IIa and Class IIb require different conformity assessment routes under Article 52, different depth of clinical evaluation, and different post-market surveillance intensity. A team that scopes a continuous patient monitor at Class IIa and discovers during Notified Body review that the vital-parameters escalation applies rebuilds a meaningful portion of its technical file.

## Rule 10 text decoded

Rule 10 in Annex VIII, Chapter III, covers active devices intended for diagnosis and monitoring. The baseline places those devices in Class IIa. Four escalation paths take specific categories to Class IIb: hazardous energy absorption, imaging of radiopharmaceutical distribution, direct diagnosis or monitoring of vital physiological processes, and ionising radiation for diagnostic or therapeutic interventional radiology.

The rule does not define "vital physiological processes" with a closed list, does not give a numerical threshold for "potentially hazardous" energy absorption, and does not resolve edge cases between Rule 10 and Rule 22. Those judgments are left to the manufacturer, constrained by MDCG 2021-24 where it offers interpretation.

## What counts as an active device for diagnosis and monitoring

An active device is defined in Section 1 of Annex VIII as any device whose operation depends on a source of energy other than that generated by the human body or by gravity, and which acts by changing the density of or converting that energy. Software on its own is also an active device.

Section 1 defines active devices intended for diagnosis and monitoring as any active device used to supply information for detecting, diagnosing, monitoring, or treating physiological conditions, states of health, illnesses, or congenital deformities. The diagnostic or monitoring purpose is the hinge. A device that delivers therapeutic energy is Rule 9. A device that only supplies information is Rule 10.

Intended purpose decides whether a device falls under Rule 10, not the hardware inside. Under Article 2(12) of the Regulation, intended purpose is "the use for which a device is intended according to the data supplied by the manufacturer on the label, in the instructions for use or in promotional or sales materials or statements and as specified by the manufacturer in the clinical evaluation" (Regulation (EU) 2017/745, Article 2, point 12). Two devices with identical sensors and firmware can fall under different classification rules depending on what the manufacturer claims. This is the mechanism startups most often miss when they classify from the bench rather than from the label.

A closed-loop system that monitors a physiological parameter and then administers therapeutic energy in response is a candidate for Rule 22, which produces Class III when the diagnostic function significantly determines patient management. Highest-class-wins then governs.

## The four escalation paths

The Class IIa to Class IIb escalations are four distinct tests. A clean rationale addresses each of them, even if the conclusion is "does not apply."

**Escalation one. Hazardous energy absorption.** The device supplies energy absorbed by the human body. Nature, density, and site of application determine whether that absorption is potentially hazardous. In Rule 9 the energy is therapeutic; in Rule 10 the energy is a diagnostic carrier (ultrasound pulses for imaging, radiofrequency for MRI, X-rays for radiography). Illumination in the visible spectrum is explicitly excluded, which is why a fundus camera with a visible-light flash does not trigger escalation one on illumination alone.

**Escalation two. Imaging in vivo distribution of radiopharmaceuticals.** Gamma cameras, SPECT systems, PET systems, and the control and reconstruction software specific to those systems fall under this escalation. The rule applies to the imaging device itself, not the radiopharmaceutical, which is regulated separately as a medicinal product.

**Escalation three. Direct diagnosis or monitoring of vital physiological processes.** Continuous cardiac monitors, continuous respiratory monitors, and EEG systems used for diagnosis of central-nervous-system activity fall here when they provide information on a process vital to keeping the patient alive. The sharpened provision then covers devices specifically intended for monitoring variations where the variation itself could put the patient in immediate danger. The text names cardiac performance, respiration, and activity of the central nervous system.

**Escalation four. Ionising radiation for diagnostic or therapeutic interventional radiology.** Radiographic X-ray systems, fluoroscopy systems, computed tomography systems, and the controllers, image processors, and workstations that directly influence their performance are captured here.

A clean Rule 10 rationale works through each of the four escalations in turn, names the facts that make each apply or not apply, and concludes with a specific class and citation. A rationale that says "the device is a patient monitor and therefore Class IIa" skips the vital-physiological-processes test entirely.

## Worked examples

**General-purpose ultrasound imaging system.** Ultrasound energy is absorbed by tissue; nature, density, and site have to be stated against MDCG 2021-24 thresholds. For most general-imaging acoustic outputs, the system escalates to Class IIb under escalation one.

**Fingertip pulse oximeter for spot checks in a general ward.** The visible-spectrum illumination carve-out and the low intensity at the site mean escalation one does not apply. Whether spot-check use counts as "direct monitoring of vital physiological processes" depends on the intended purpose statement. Many spot-check pulse oximeters stay in Class IIa, while devices labelled for continuous monitoring in acute care escalate to Class IIb.

**Continuous bedside patient monitor with ECG, SpO2, respiration, and invasive blood pressure.** Escalation three applies: the device continuously monitors cardiac performance, respiration, and haemodynamic parameters; variations can put the patient in immediate danger. Class IIb.

**Fundus camera with a visible-light flash.** The visible-spectrum carve-out applies; no other escalations fire. Class IIa.

**Computed tomography scanner.** Escalation four applies. Final class: Class IIb. The control console and reconstruction workstation that directly influence the scanner also fall into Class IIb under the same paragraph.

**PET scanner.** Escalation two applies. In a PET/CT configuration, escalation four can also apply. Final class: Class IIb, with highest-class-wins resolving any overlap.

**Electrocardiograph for resting 12-lead ECG in outpatient use.** Simple resting ECG without alarming is often Class IIa, while a device intended for diagnostic use in situations where the patient is in immediate danger escalates to Class IIb under escalation three. The intended purpose statement decides.

## Common misclassifications

**Defaulting every active diagnostic device to Class IIa.** The baseline only holds when none of the four escalations fire. Skipping the escalation tests is the fastest way to classify a Class IIb device as Class IIa and meet a Notified Body dispute.

**Missing the vital-physiological-processes escalation on continuous monitors.** A wearable patch that continuously measures ECG, respiration, and activity is not automatically Class IIa just because the Rule 10 baseline is Class IIa. Escalation three has to be analysed explicitly.

**Treating every visible-light imaging device as exempt from escalation one.** The carve-out is for illumination in the visible spectrum. It does not exempt a device that also delivers non-visible energy, or one that delivers visible light at intensities producing tissue effects beyond simple illumination.

**Classifying imaging workstations as standalone accessories.** A workstation that directly influences the performance of a Class IIb imaging device under escalation four is itself captured by the same escalation.

**Missing Rule 22.** A closed-loop diagnostic-therapeutic device where the diagnostic function significantly determines patient management falls in Class III under Rule 22. Always check Rule 22 for combined-function products.

**Missing Rule 11 for standalone diagnostic software.** Standalone software intended as a medical device on its own is classified under Rule 11. A cloud-based algorithm that reads ECGs uploaded from third-party devices is not a Rule 10 device.

## The Subtract to Ship angle on Rule 10

Rule 10 is the other half of the active-device pass in the [Subtract to Ship framework for MDR compliance](/blog/subtract-to-ship-framework-mdr). The discipline is to find the lowest defensible class, not the lowest class the team hopes for. A rigorous four-escalation analysis that lands on Class IIa and survives Notified Body review is subtraction done right. A thin argument that collapses under review is not a shortcut. It is rework waiting to happen. Baseline, four escalation tests, facts for each conclusion, rule citation, MDCG 2021-24 cross-reference. Anything longer is usually padding.

## Reality Check. Can you defend your Rule 10 classification?

1. Have you written the intended purpose in the exact terms that will appear on the label and instructions for use, not in engineering shorthand?
2. Have you confirmed the device is an active device for diagnosis and monitoring, not an active therapeutic device (Rule 9) or standalone software (Rule 11)?
3. Have you addressed escalation one (hazardous energy absorption) with the nature, density, and site of application documented?
4. Have you addressed escalation two (imaging in vivo distribution of radiopharmaceuticals)?
5. Have you addressed escalation three (direct diagnosis or monitoring of vital physiological processes) and checked whether variations could put the patient in immediate danger?
6. Have you addressed escalation four (ionising radiation for diagnostic or therapeutic interventional radiology) and classified controllers and workstations that directly influence performance under the same escalation?
7. Have you cross-checked against MDCG 2021-24 (October 2021)?
8. Have you checked whether Rule 22 also applies, and if so, taken the higher class?
9. Could you hand a Notified Body auditor a one-page rationale tomorrow and walk them through each of the four escalations without improvising?

## Frequently Asked Questions

**When does Rule 10 escalate from Class IIa to Class IIb?**
In four situations: when the device supplies energy absorbed by the human body in a potentially hazardous way (with an exception for illumination in the visible spectrum), when it images in vivo distribution of radiopharmaceuticals, when it allows direct diagnosis or monitoring of vital physiological processes (with a sharpened provision for monitored variations that could result in immediate danger), and when it emits ionising radiation for diagnostic or therapeutic interventional radiology. MDCG 2021-24 provides worked examples.

**Does Rule 10 cover therapeutic devices?**
No. Rule 10 covers active devices intended for diagnosis and monitoring. Active devices intended to administer or exchange energy for therapeutic purposes fall under Rule 9. Combined diagnostic-therapeutic closed-loop devices may fall under Rule 22, which produces Class III when the diagnostic function significantly determines patient management.

**Is a pulse oximeter Class IIa or Class IIb under Rule 10?**
It depends on the intended purpose. A spot-check pulse oximeter for general ward use is often Class IIa. A pulse oximeter labelled for continuous monitoring in acute-care settings, where variations in SpO2 can put the patient in immediate danger, is typically Class IIb under escalation three.

**Does Rule 10 apply to standalone diagnostic software?**
No. Standalone software intended as a medical device on its own is classified under Rule 11, regardless of whether its purpose is diagnostic or therapeutic. Rule 10 applies to active hardware devices and their embedded software. See MDCG 2019-11 Rev.1 for standalone software classification.

**How does a Notified Body assess a Rule 10 classification rationale?**
A Notified Body expects a written rationale that states the baseline, addresses each of the four escalations explicitly, names the facts that make each apply or not apply, and cross-references MDCG 2021-24 where applicable. A rationale that only addresses one or two escalations will be challenged.

## Related reading

- [The Subtract to Ship Framework for MDR Compliance](/blog/subtract-to-ship-framework-mdr) – the methodology behind the rule-by-rule classification pass.
- [MDR Device Classification Explained](/blog/mdr-device-classification-explained) – the pillar post on how classification works across all four classes.
- [MDR Annex VIII Classification Rules: The Complete Guide for Startups](/blog/mdr-annex-viii-classification-rules-complete-guide) – the full rule-by-rule walkthrough of Annex VIII.
- [How to Apply MDR Classification Rule 9: Active Therapeutic Devices](/blog/mdr-rule-9-active-therapeutic) – the sibling rule for therapeutic energy exchange.
- [How to Apply MDR Classification Rule 11: Software as a Medical Device](/blog/mdr-rule-11-software) – the software rule that applies to standalone diagnostic algorithms.
- [Notified Body Classification Disputes: How to Defend Your Position](/blog/notified-body-classification-disputes) – what happens when the Notified Body disagrees with your Rule 10 call.

## Sources

1. Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, Article 2(12) (intended purpose), Article 51 (classification), Annex VIII Section 1 (definitions), Section 2 (implementing rules), Chapter III Rule 10 (active devices for diagnosis and monitoring; active devices emitting ionising radiation). Official Journal L 117, 5.5.2017.
2. MDCG 2021-24. Guidance on classification of medical devices, October 2021.

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*This post is part of the Device Classification & Conformity Assessment series in the Subtract to Ship: MDR blog. Authored by Felix Lenhard and Tibor Zechmeister. The Rule 10 analysis above is an orientation layer. Classification of a specific device must always be made against the full text of Annex VIII, cross-checked with MDCG 2021-24, and documented with the rule citation, the four-escalation test, and a defensible rationale.*

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*This post is part of the [Device Classification & Conformity](https://zechmeister-solutions.com/en/blog/category/classification) cluster in the [Subtract to Ship: MDR Blog](https://zechmeister-solutions.com/en/blog). For EU MDR certification consulting, see [zechmeister-solutions.com](https://zechmeister-solutions.com).*