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Brittney McIver


Everything You Need to Know About Root Cause Analysis

Every CAPA should begin with investigation

Published: Wednesday, April 20, 2022 - 11:02

At some point, every medical device company will encounter an issue that requires an internal investigation. Whether it’s due to a nonconformance, complaint, CAPA, or an audit issue, you’ll have to conduct a failure or root cause investigation to pinpoint why the issue occurred in order to resolve it.

For many companies, the news that they need to conduct an investigation may be accompanied by a sense of dread. It’s never pleasant to think about the implications of anything going wrong with a medical device. But don’t let that put you off the heart of the matter.

An investigation can be an excellent learning mechanism—an opportunity for your business to gain valuable insights that spark process and product improvements that will only serve you better moving forward.

That said, investigations can be confusing for many medical device companies. So, let’s dive deeper into understanding root cause analysis as a high-level concept, what kinds of steps are involved, and the primary methodologies that are used.

What is root cause analysis?

Root cause analysis is a method that helps you understand both the primary cause of a problem and why a problem occurred in the first place. Through a variety of approaches, techniques, and methodologies, root cause analysis empowers medical device manufacturers to identify the root cause of an issue, rectify it at the source, and prevent it from happening again.

Root cause analysis is an essential component of corrective and preventive action (CAPA), as well as customer complaints, nonconformances, and audits. In ISO 13485, the process of identifying root causes and applying necessary controls to prevent similar issues is required for quality management systems, specifically in an organization’s continuous improvement efforts.

As with any quality management system (QMS) procedure, root cause analysis alone does not produce any specific results. Rather, the action taken on the root cause, as well as the effectiveness of said action, produces the results.

What does a root cause analysis involve?

The steps of a root cause analysis involve procedures to determine what caused the device to break, why it happened, and how you can prevent it from happening again in the future.

Of course, you’ll need to contain and resolve the issue at hand as soon as possible. But the end goal should be to correct the systemic problem and prevent it from reoccurring. A successful root cause analysis will almost always involve some variation of these steps:
Create a problem statement. Define the problem taking place by gathering all relevant data and evidence about the current situation. Using the information you collect, your statement should specify the actual impact, potential impact, the focal point of the problem, etc. Keep this statement as concise as possible.
Determine the factors that caused the problem. Gather a team of stakeholders directly involved in this process along with any other experts whose input will be valuable. As a team, brainstorm the possible factors for the problem by uncovering the “why.”
Identify the root cause. Dig deeper by continuing to ask why after the first layer of causal factors. Keep at it until finally you discover the fundamental cause of the problem at hand. Determine which corrective actions must be taken to eliminate the problem and prevent it from reoccurring in the future. Make sure you clearly communicate these corrective actions to the people who will be involved.
Review and evaluate the effect of the corrective actions. Determine if the actions can be declared “effective.” If not, make improvements as necessary.

As with any form of a risk-based approach that is taken within a QMS, documentation is a key component for a successful root cause analysis. Not only does documentation provide traceability for future internal investigations or external audits, it also ensures that any relevant controls are followed to the letter.

In the case of root cause analysis, documentation generally takes the form of established methodologies, tools, and templates.

Types of root cause analysis methods

There are several methods for identifying the real root cause of an issue and coming up with the corrective actions needed to prevent it from happening again.

Here are a few of the most common methods to consider when conducting your own analysis:

‘5 Whys’ root cause analysis

As the name suggests, in the “5 Whys” analysis, the question “Why?” is asked five times in the course of finding the root cause of a problem.

To carry out a 5 Whys root cause analysis, you need to gather a team of people who are affected by the problem.

Once you have asked why five times and figured out the root cause, come up with an improvement measure you need to apply. Assign corrective and preventive actions to the members of the team you assembled.

5 Whys
“5 Whys” root cause analysis

Cause and effect analysis (fishbone or Ishikawa diagram)

Once you have identified the problem, you can use the cause-and-effect analysis to explore the causes of a problem and its effects. An example of this would be a “fishbone” diagram.

Just as it helps explore the factors that are preventing an outcome, a fishbone diagram can also be used to identify the factors needed to generate the desired outcome.

Fishbone Diagram
Cause and effect analysis using a fishbone diagram

Fault tree analysis

Fault tree analysis is a deductive analysis that visually represents the failure path. You can use fault tree analysis to determine the possible causes of a problem or an event. The fault tree starts with the event at the top, and the possible causes are placed below.

Fault tree analysis
Fault tree analysis

Pareto chart

A Pareto chart is a combination of a bar chart and a line graph. The length of the bars represents the frequency or cost of faults, and they are arranged in a way that highlights the most frequent to the least frequent. The chart helps prioritize your issues based on the cumulative effect they have on a system.

The Pareto chart is based on the theory that 80 percent of the total problems that occur result from 20 percent of the problem causes, referred to as the 80/20 rule. This means if you have solutions to your major problems, you can also solve a majority of your other smaller problems.

Pareto chart
Pareto chart

Scatter diagram

Scatter diagrams, or scatter plot diagrams, can be used to visualize the relationship between two variables. Once you have created a cause-and-effect diagram and identified potential causes to your problem, you can use the scatter diagram to determine which causes are responsible for the variation.

This is possible because the scatter plot uncovers relationships in data. Due to the ease of manipulation in the independent variable, finding correlation means that there is some pattern between X and Y. However, the scatter plot can never “prove” the cause and effect, because this must be established with the researcher’s scientific process.

The independent variable is plotted along the horizontal axis, and the vertical axis is for the dependent axis.

Scatter diagram
Scatter diagram


Failure mode and effects analysis (FMEA) is a systematic method for evaluating a process. It can be used with the premise that a failure has already happened for which you’re trying to identify the cause and severity of the failure mode, or it can be used proactively.

This would mean assuming a failure or evaluating a process to determine where it might fail, then taking steps to manage any parts of the process that appear prone to failure.

Tips for conducting root cause analysis investigations

There are a few key issues that commonly trip up medical device companies. These are often found in the tools used for conducting an investigation. Here are a few tips for getting through your investigation procedures:
• Don’t get hung up on the tool you use. Many businesses let the tool get in their own way by choosing a method that they are not familiar with, hampering them unnecessarily. Find something you can work with and stick with it.
• Overuse of FMEA is a common mistake. Usually, FMEA is a very good tool if you’re trying to design your manufacturing process or have a singular event that could lead to a failure. If you try to apply it to the use of your product, there tends to be too many variables. When it comes to product use, risk analysis usually requires a sequence of events to occur to lead to the failure, whereas FMEA is better suited for singular events.
• Methods such as fault tree or fishbone are better when a series of events is involved.
• If root cause analysis is new to you, start with the simpler tools. We recommend fishbone or 5 Whys as good methods to start with.
• Don’t investigate in isolation. A single person will come up with results directly dependent on their own experience. Bring in cross-functional resources to brainstorm—who else has the knowledge?

Get to the root cause faster with software

Part of improving your root cause analysis process is having the right tools in place. Software, like that from Greenlight Guru, makes it easy for companies to effectively manage not just their risk-based CAPA processes but also the connected activities of customer complaints and nonconformance management, all in a connected ecosystem where inputs and outputs tell the true story.

This kind of tool allows you to take the necessary steps to properly define the root cause and trace CAPAs back to their root cause, even if it’s related to design control. In turn, you’ll be able to ensure your corrective and preventive actions are more effective in the long run by providing a verification workflow for your CAPA.

First published March 27, 2022, on the GreenlightGuru blog.


About The Author

Brittney McIver’s picture

Brittney McIver

Brittney McIver is a medical device guru at Greenlight Guru and biomedical engineer who works with customers to utilize their eQMS software to streamline processes and maintain audit-ready, regulatory compliance. She began her journey as a quality engineer responsible for carrying out complaint investigations and leading quality system efficiency and improvement efforts. She then continued her career as a project engineer in medical device manufacturing, specifically in polymer extrusion. She loves quality processes and strives to inculcate a culture of quality in her customers so they can continue to improve patients’ quality of life with their amazing technologies.