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A Guide to Worst-Case Testing in MedTech

Updated: Feb 7

💥 A Meteorite Strikes and the Sky Falls on Us – The Art and Science of Defining Worst-Case Tests in Medical Technology.

We believe that there is a lack of guidelines around the topic of worst-case testing in the medical device industry.

In this short but comprehensive article we give you an essential overview of what you need to consider when doing worst-case testings in MedTech.

Worst-case testing in MedTech

Countless standards and guidelines talk about "worst-case", either from a use, product, process, or test perspective. Even though we all use the term "worst-case" in an inflationary manner, we know little about it.

An excerpt of standards that include worst-case considerations are:

  • ISO 10993-1

  • ISO 11607-1

  • ISO 19227

  • ASTM F3263

  • ASTM F3127

  • and many others

Unfortunately, we often refer to a "worst-case" without really having it defined nor documented. In the following, we will give you some ideas and guidance on what to consider when defining a worst-case and how to document it.

1) Worst-Case: Introduction

Highlight the importance of worst-case scenarios for safety, effectiveness, and compliance. Stress the need for a versatile, systematic approach applicable across various product families and/or processes.

2) Worst-Case: Scope and Purpose

  • Clearly define the scope of the worst-case scenario, specifying its intended application (e.g., process validation, design verification, cleaning validation, etc.).

  • State the purpose, emphasizing risk mitigation, compliance, or process optimization.

3) Worst-Case: Identify Critical Parameters

  • Identify the key parameters that significantly influence safety, efficacy, or compliance of the product or process.

  • Consider factors such as materials, environmental conditions, user interactions, and potential failure modes.

4) Worst-Case: Assess Variability

  • Evaluate the variability associated with each critical parameter.

  • Determine the lower and upper limits, considering both typical and extreme conditions.

5) Define Worst-Case Conditions

  • Develop a matrix or framework that combines critical parameters and their variability.

  • Select worst-case conditions by identifying the most extreme values or combinations of parameters from the matrix.

An example of worst-case testing

Worst-case testing in MedTech

Please note that the matrix provided is solely an illustrative example and is neither accurate nor exhaustive in representing the full scope of a specific scenario.

5) Worst-Case: Documentation and Rationale

  • Document the rationale behind the selection of worst-case conditions (see Table 1).

  • Include detailed information on how each parameter was evaluated and why specific conditions were chosen.

6) Worst-Case: Monitoring and Adaptation

  • Emphasize the need for ongoing monitoring and reassessment of worst-case scenarios (e.g., product and/or process changes; is the worst-case still applicable?).

  • Acknowledge that technology, regulations, or other circumstances may change, requiring updates to worst-case definitions.

We wrote this article due to the lack of guidelines around that topic. Many standards call out worst-case considerations with sometimes limited information.

This article should help you navigate, document, and monitor the task of worst-case testing.

What is your experience with worst-case testing? Do you have specific questions questions or valuable insides on this topic? As always, we appreciate if you leave us a comment below.

Simon Föger, CEO SIFo Medical

Author: Simon Föger

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