MedTech Expert Explains Cleaning, Disinfection & Sterilisation | Pressure Tested

I’m Chris, an expert in medical device validations, and I’m here to be pressure tested. I’m going to answer some easy, medium, and hard questions based on cleaning, disinfection, and sterilization validation.

Right. So I suppose we’ll start with the first question.

What is a reusable medical device?
It’s quite a good question. So this can be as simple or as complicated as you choose for it to be. In simple terms, a reusable medical device is a reusable device that’s used between different patients and end users, all while making sure that they remain safe. And that means there’s some additional testing a reusable medical device needs to go through before you can actually call it reusable.

I suppose for the next question:

What is an IFU?
Very nuanced topic. So in simple terms, once again, an IFU is an instruction for use manual. Think of it like a guidance documentation provided with just about every single medical device, and it details how to use that medical device, how to reprocess that medical device, any indications and contraindications you might need to know about, the intended population, and most importantly, who this should never be used on under any circumstance.

Following a proper IFU is a very important thing for your medical device’s life cycle to last as long as possible. I get this one quite a lot, actually. What do I need to include in my IFU manual? So this really depends on how much experience you have with the MDR process as a whole. The things that should go in your IFU are very explicit, and they’re made clear specifically within the standard called ISO17664-1 and 2. Those standards will basically detail exactly what needs to go into your IFU, what evidence you need to provide with the contents of your IFU, and how you should go about essentially validating those pieces of evidence.

But long story short, you basically need cleaning instructions, disinfection instructions, and sterilisation instructions. You also need to state exactly how long of a life cycle you’re going to give your device in your IFU and make sure any maintenance instructions that need to be within that IFU are in there. That’s the key point to making sure the end users have a good experience with your medical device.

The next question I get quite a lot from manufacturers who don’t have as much experience within this setting as a whole.

What is cleaning, disinfection, and sterilisation validation?
So essentially, when you term your medical device as reusable, it needs to go through reprocessing before it’s fit for reuse on another patient, for example. Part of that reprocessing includes a cleaning process, a disinfection process, and a sterilisation process. Cleaning and disinfection, at least in the UK and Europe, are typically done in a device called a washer disinfector, and this is specifically designed to clean and disinfect medical devices to a very high grade so we can all be assured the sort of patient that these are getting used on remains safe, right?

Sterilisation is typically more done in autoclaves, and essentially it’s a pressurised chamber with very high-temperature steam. Think 134 degrees, for example. And essentially, the pressure keeps the medical device from essentially being ruined within that process. And essentially all that’s doing is bringing your device up to a very high temperature so we can all be assured it’s sterile before it’s used on the next patient.

The next question is a bit more complicated.

I have a product with cleaning, disinfection instructions suitable for the FDA. Is it sufficient for the European market?
This is a very nuanced topic, and it’s going to heavily depend on your medical device and exactly what you’re trying to prove, with which market you’re trying to be in compliance with.

You can be in compliance to both the FDA side and the MDR side, but you’re going to need some level of justification within your technical file, as well as some robust evidence to make sure that both sides are happy with what you’ve done. Rule of thumb is typically the FDA side, under the AAMI guidance, they tend to be almost more accepting of equivalence. Whereas on the MDR European side, they take a more risk-based approach, and they really put an emphasis on making sure you have tested your evidence for your particular medical device.

I would suggest you speak to a consultant or someone like us at Test Labs, who are experts in the field, and we can help you navigate your way around this. It’s a very complicated topic.

The next question is:
What’s the biggest mistake in cleaning, disinfection, and sterilisation validation?
It’s quite a good question. I wouldn’t focus too much on exactly those processes. The biggest thing to focus on is always your intended purpose, way at the start of when you started designing your medical device. As long as the cleaning, disinfection, and sterilisation do not impede your intended purpose for your medical device, you’ll almost always be in the clear.

So just make sure you get that right before you get to the stages of validating and producing evidence for your claims. Make sure your claims are exactly as you want them to be.

As for the next question:

What are the key standards for cleaning, disinfection, and sterilisation?
So all standards are just a way for us to standardise testing across the entire industry so that all the evidence that’s provided to the notified bodies and the regulators, it’s all sort of following the same framework.

For reusable devices, the guidance starts with a standard called 17664-1 for critical devices, and dash 2 for non-critical devices. That standard explains to you exactly what needs to go in your IFU if your device is reusable. It also tells you exactly which standards to employ to validate those claims for your cleaning, your disinfection, and your sterilisation.

Cleaning, that follows guidance under the 15883-1 to 5 framework of standards, which basically define how to use a washer disinfector, and more importantly, how to validate evidence coming from a washer disinfector. And then you have 17665, which essentially will explain to you every aspect of sterilisation using an autoclave, all the way from manufacturing to within the laboratory environment, proving those claims and generating evidence. On the FDA side of things, you have ST98, which basically would describe the cleaning validation as well as the experimental conditions you need in place to make sure you’re validating cleaning correctly. There is also the ST79, I believe. That’s the sterilisation equivalent to the European side of things. And then there is TIR30, which is a very large compendium with a lot of information, not just on cleaning, but on disinfection, sterilisation, and other aspects of medical devices as well. The last one I haven’t mentioned is TIR12, which is some of the only guidance available in the industry for validating manual disinfection instructions.

The next question is quite important because I get it a lot from different manufacturers.

I have thousands of products in my family. Do I need to test each of them?
So typically, a lot of manufacturers have massive portfolios of medical devices. But the key thing is there is very little difference in those medical devices. So let’s say, for example, you have 3,000 medical devices within your portfolio. You could probably group those into specific medical device families, and then from each family, pick the medical device that represents the sort of design features of that family the most. And then all you would do is perform validation and generate evidence using those worst-case devices. And basically, you would then justify that your entire portfolio has been validated based on the cleaning, disinfection, and sterilisation performed on these worst case devices.

Now, the next question would be:
How would you decide what’s a worst-case device and what’s not?
This is where you need an expert to help you, and I would encourage you to either have a structured dialogue with your notified body or seek out consultants, maybe even us at Test Labs. It takes a lot of guidance and justification to make sure that when you say it’s a worst-case device, that you mean it.

When should cleaning validation begin in development?
So when you start generating evidence for your claims, it’s probably around the, you’re just about ready for submission. The key point is that the medical devices you’re generating evidence on are in the state that you would, for example, ship them to your end users. As long as the evidence is generated on the final design of your medical devices, everything’s going to be fine. As for when to do it, so unfortunately, with the MDD to the MDR transition, there is a massive backlog on every single aspect of medical device testing in general. And the answer to that is as soon as possible.

Start testing, start planning, start setting aside your budget as soon as possible because you cannot afford to waste time on retests and having to go back and re-examine your technical file. Imagine if you miss the date you’ve, for example, scheduled with your notified body. That’s another year of waiting. So my key takeaway would be start as soon as you can.

What slows sterilisation validation down?
So with these sorts of processes, it’s usually the things you never even thought to consider that end up being the things that halt your entire evidence-generating process. For example, with sterilisation validation, most manufacturers might sort of hope as long as the device gets to a certain temperature within an autoclave, you’re fine. Unfortunately, there are other considerations. For example, drying validation within an autoclave. After sterilisation, how dry are your medical devices? Are you at risk of forming a wet pack, in which case the entire validation is void? Number two, what packaging are you recommending your device be packaged in during sterilisation? Because different packagings have different levels of steam penetration, which will increase or decrease the sterilisation efficacy you’re going to get with your medical device.

Another thing you might not know is that the actual packaging itself also has EN standards that it needs to meet to make sure that it’s also doing its job properly within the autoclave. So it’s always the things you never thought to look at that end up being the biggest issues. And once again, it’s so important to have an expert with your side when you’re navigating this process. The next question is actually getting– We’re getting quite difficult now.

How do you validate worst case devices correctly?
There is no correct way to validate devices. The process is an evidence-generating based process, and it’s going to be different for every single medical device. Some devices will be easier to clean than others, but will be harder to sterilise than others. Some devices can’t be sterilised, in which case disinfection would be the terminal process. Therefore, we might need to look at manual disinfection, look at the FDA’s cleared sterilants list and see what we can do with that. The most important thing is that the evidence you’ve generated backs up your claims. And for that to happen, you need an expert with you. The common sort of pathway of this is that you would basically perform a cleaning validation towards the applicable standard for your market. As long as that’s passed, and cleaning validation tends to be the hardest process to pass on, the thermometric and sterilization validation would follow afterwards, and you would just sort of knock those out right after the cleaning validation, and that should be fine.

What causes repeat sterilisation studies?
I think this is being looked at in the wrong perspective. The actual question is, what causes sterilisation validation to fail, and how can I avoid that? And once again, this is where that worst-case justification comes in. If you’ve done your due diligence, shrink down your portfolio to the worst-case sterilisation devices, you should have an idea, or at least your expert should have an idea of what’s going to cause you to fail this device. Typically, among all of the thousands of devices I’ve tested, something that’s very dense and very large will probably fail sterilisation validation. It’s a thermometric test where you basically prove that something was at 134 degrees, for example, for a three minutes length of time. But if something is very dense, for example, the surface might reach the correct temperature, but the internals of your device absolutely will not reach 134 degrees. In which case, you run the risk of getting false positives, for example, false negatives, where one result might say your evidence is fine, but down the line, you might find out it’s not fine. The key point is to basically assess your device, see how compatible it is with your sterilisation process, and then keep that in mind before you perform the testing. The point of testing is to see what needs to change. So a failure is never the end of the world. In fact, a failure is good because now you know exactly what needs to change with your device, and the regulators will love to see that you actually did do your due diligence, you did test properly, and you did implement the corrective actions to make sure your device is fit for purpose and safe for the patient to use.

The next question is actually quite nuanced, and it’s in a very niche area.

How does material compatibility and sterilisation interact?
So it’s very, very key for us to remember here that sterilisation validation is only validating that the instructions you give the consumer will lead to your device being sterilised properly, even in a worst-case scenario. Material compatibility is something you should already have data on before you get to validating any IFU processes. Material compatibility is basically where you figure out if the processes and the detergents or high temperatures you’re introducing to your device are going to have an adverse impact on the materials that make up your medical device.

An IFU, even if it can clean, disinfect, and sterilise properly, is almost worthless if it reduces the life cycle of your device to, let’s say, 30 days because it basically ruins the materials that make up your device. Now, when you start to design your device, it’s very key to look up the SDSs and material data for these materials you’re using for your device because you should have a strong idea of what you can and can’t do with your device before you get to validating any processes surrounding that device.

What’s the one thing manufacturers underestimate about cleaning validation?
So I think this is where it becomes very market-dependent. The unfortunate truth is that across the world, not everyone has access to the sort of main pathways a cleaning validation might take.
For example, if you validate your cleaning instructions using a washer disinfector, if your end user doesn’t have regular access to a washer disinfector, the instructions weren’t really fit for purpose in that market you sort of sold the medical device in, right? I think we can all agree on that. And in fact, the guidance from the MDR, for example, makes sure to state that whatever evidence you generate, make sure it takes the market you’re doing business into account, basically. So another thing to touch on here is that cleaning can be very easy or very difficult, depending on how you’ve designed your devices.

And you might have to consider including some accessories to help with cleaning of the medical device. So do not underestimate the fact that because it’s in a washer disinfector, an automated process. Don’t underestimate how hard and challenging a validation can be if the point is to prove safety for a patient at the end of all of this. It’s a quite involved process, and I would recommend you really, really, really consider the design of your device at the inception before you get to… the end where you’re doing a validation and you realise, oh, there are a lot of matted surfaces on this device.

It’s going to be impossible to clean properly. What do we do? Don’t get to that point, and make sure you’re prepared.

What data do I need to present to regulators?
So this is now quite a hard question to answer. The easiest way to go about this is to follow the guidance. The evidence you need to give to your notified bodies and regulators is explicitly made clear in documents like 17664, for example, as well as some of the attached MDR documents. Your notified body should also have a checklist they can send you, which will basically detail every single aspect of evidence that needs to be within your technical file based on your intended purpose. So I think the easiest way to go about this is to just talk to your notified body, have a structured dialogue, follow that checklist they present you, and that’s going to lead you on to where you need to go next.

Typically, you start with the easy justifications, the easy intended purposes, your risk-based approaches, and what you’ve done to mitigate that risk before you start generating any evidence. However, what you need to provide is made very clear. And don’t deviate from that. Otherwise, that’s what makes the process take a while, basically. Just follow their guidance, follow the checklist, and let’s go from there. The next question is actually very pertinent to the current timeframe. My products have been on the market for the last 30 years with no issues.

Do I need to perform a revalidation?
So this is the thing with guidance. It evolves over time as we learn new things that we didn’t previously know before. Chances are, if you haven’t produced any evidence for your medical device in the last 30 years, you are behind on what you need to have as evidence for your device. What typically happens is that it’s not an issue until someone raises it as an issue, and then you’re basically caught unprepared. You might need to suddenly come up with hundreds of grand worth of testing finances to be within compliance again, but that’s going to take a long time. Chances are, if your evidence is over 10 years old, you really should be revalidating and re-looking at your technical files and just making sure that your quality department is happy with how your evidence presents to the current requirements.

Now, the next question is more laboratory-based, and this is, how long do cleaning, disinfection, and sterilisation validation take? So the inception of this is that basically, I’ll use Test Labs as an example. So you might contact us, and we basically have a mini consultancy session where we basically would help you and tell you exactly what you need and what you don’t need and exactly what we expect you guys to provide us as medical devices for the best possible evidence to be generated.

After that, then there needs to be a protocol, because within your technical file, you need to have a document describing exactly how testing was done and why things were done in a certain way and which standards and evidences you referenced to make your evidence better. So that usually takes about a week to three weeks, depending on your requirements.

After that, you then go through to actually doing the analytical work within the lab, for example. That usually takes anywhere from three to four weeks, depending on how complicated the process ends up being.

After that, it’s essentially just getting your report, making sure that you’re happy with the evidence generated, and then submitting to your notified body when you’re ready.

Naturally, there tends to be some questions throughout the process, and that’s where you can count on your experts or the lab you’re working with, us, for example, to answer those questions on your behalf or let you know where the evidence is that you need to answer that question.

And the next question now is very specific to cleaning validation, and that is, so…

During cleaning validation, how do I choose the best test soil to represent my medical device?
Good question. So there is guidance in two to three specific places. So 15883-5, TIR 12, ST 98, as well as some supplementary standards for test soils and test soil justification. They basically list all of the readily available test soils that everyone within the industry tends to use. And those test soils, you can either make them yourself or you can buy them commercially available. They are made up of different components based on your medical device.
For example, an orthopedic device, I would suggest that your test soil be made up of, for example, egg yolk to provide the protein component, hemoglobin to provide the hemoglobin component, and something like hog mucin to keep the mixture together and keep it very representative, keep it very difficult to remove from the device, because the harder it is to clean, the more robust the evidence you provide at the end is.

So always make sure the components within the test soil mirror where your device is going to be within the human body.

For dental medical device, for example, I would hope that your test soil has some aspect of saliva and bone fragments in it. And then, for example, for ophthalmic devices, you should probably be considering something in the human tear film to add to your test soil to just really, really, really make your evidence that much better.

And the next question is…

How many samples do I need to provide for testing for cleaning validation, disinfection validation, and sterilization validation?

So this depends on the lab and how robust they’re being with the level of evidence they’re generating for you. Us at Test Labs, for example, we would expect for cleaning validation, at least five replicates of the worst-case devices that you’re sending to us. So for example, if you are sending us six different worst-case devices, I would expect five of each of those devices to be sent to us. For disinfection, it’s typically just three replicates of your worst-case devices, and for sterilsation validation, it is four replicates of your worst-case devices, which in total basically comes up to about 12 replicates per worst-case device.

So if you have six worst-case devices, I would expect something around 60 medical devices in quantity to be shipped to us in total for your validation, for example.

Well, that was quite something. I do feel pretty tested, although there could’ve been more questions. I think the key takeaway here is that the medical device industry is very complicated, and the guidance that you need to know and follow is split between different markets. It’s split between different standards. If you have no experience going into this, it’s going to be a difficult and long process, and I would always suggest the very first thing you do as a manufacturer if you are unsure, is to reach out to a consultant, have a structured dialogue with your notified body, or reach out to industry experts like us at Test Labs and just get a conversation going to really let you know where you are, the finances you might need to invest into this, and the current scape of the industry before you jump in. Always consult someone who at least has some idea of what’s going on in the industry before you dive in. I promise you, it will save you a lot of time at the end of this.