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How do I know these embryos are really ours?

This article appeared in the media a week or so ago:

(you can read the entire article via the link at the bottom of the blog)



Absolutely devastating for both of the families concerned, not to mention the clinic, the embryologist and all the other staff involved in the case.


This kind of thing is a career ending mistake and has changed not only the lives of the two children concerned and their families, but also the entire lives of the embryologists and staff involved.


I think I can safely say that for the bulk of the patients I have supported through IVF, this is their single greatest fear - How do I know that this embryo is actually MINE? And was created using the right eggs and the right sperm??


I have spent close to 20 years reassuring people that mix ups virtually can’t happen, that embryologists are awesome, that we are highly trained and have countless processes and take every precaution possible and the chances of a mix-up are so miniscule as to be virtually non-existent… but obviously, we are humans… and humans make mistakes…


And, society is moving at a rate of knots - people need more than just placations from their medical professionals - it’s not enough anymore just to say ‘trust me’ (that's a topic for another post!!)


So, I wanted to break it down a bit for you and help you to understand the measures that your embryologists take to ensure that mix-ups like the one described here are avoided at all costs.


There are a number of ways that embryologists can keep track of eggs, sperm and embryos in the lab. The first one is obviously your name. When you have an egg collection, or your sperm is received by the lab, the scientist responsible will ask you for your full name and date of birth. This will be double checked against any paperwork that the lab have and the labels on any dishes and tubes that are being used for that step in the process.


Labels on dishes and tubes usually contain three separate identifiers: Full Name, Date of Birth and a unique ID code. This is a combination of letters (your name) and numbers (your birthdate and ID number) as it is well known that humans are either good at reading letters, or good at reading numbers, or conversely - are more likely to transpose letters or numbers, but rarely both.


Traditionally, these three items were hand written on every single test-tube and dish used for your treatment cycle in a single colour unique to you that day. So if there were 5 egg collections that day, each patient would be allocated a colour and all of their information would be hand written in the same colour - paper notes, test tube labels and dish labels.

(we actually did a huge study in the lab I worked in back in the early 2000’s looking for the least toxic marker to use when labelling dishes and tubes!)


Each time any patient material was moved from one container to another (ie from egg collection dish to storage dish, from sperm collection pot to sperm washing test tube, from one test-tube to another or from one dish to another), the embryologist doing the procedure would call over a second embryologist to check both test-tubes, or dishes and the paperwork and ask them to ‘witness’ that all of the identifying details were the same - same names, same DOB, same ID number and same colour. This ‘double witnessing’ required both embryologists to read out loud all of the information on each dish/tube/paperwork - confirming that all details were correct.


Being human means that we automatically skim read, some people will miss place letters in a word, some people will miss place numbers in a string of numbers and some people see colours differently. So by having a combination of each of these, we reduce the risks that things will be read incorrectly.


This kind of human witnessing requires certain lab staffing levels so that someone is available at all times for witnessing - and quickly too - activities inside an embryology lab are all time-sensitive so prompt witnessing is really important. This means that at least 2 embryologists need to be present in the lab at all times.

It also requires that staff are well rested (ie get their breaks, meals and days off when they're rostered to avoid burn out)


When I worked in the Rockhampton lab by myself, I didn’t have anyone to witness - especially on weekends when I was the only one in the clinic. During the week I sometimes used the nurse, or an administrator but on weekends, I had to do my own witnessing. This involved reading the label out loud, then turning away, actively reading something else out loud and then turning back and reading the second label out loud.


How long have we been doing it?

This technique of witnessing, known as ‘human double witnessing’ was considered standard in Australian labs when I started my embryology training in Melbourne in the year 2000 after having been introduced by RTAC (Reproductive Technologies Accreditation Committee) in 1998 and vigorously policed through routine inspections of all Australian IVF clinics.


When I went to work in Sweden in 2002, I was surprised to discover that witnessing was not mandatory, or even part of the guidelines! The embryologists I worked with wondered why I kept asking them to double check me and make sure that the gametes I was handling belonged to the right people. At one point they even suggested that perhaps I was not confident with my ability to read or do the work required!

By the time I left that clinic, they were just considering adding witnessing as a step, but were conscious it could create difficulties in work-flow, and as they had never (that they knew anyway!) had a mix-up occur in their lab, it was difficult for them to see the benefits of the added pressure on embryologists to witness every step. Some of the embryologists even saw it as a judgement on their ability to do their jobs safely.


When I was working in the UK in 2003, human double witnessing was standard practice having been made compulsory by the HFEA in 2002. Discussions around some kind of automated witnessing were brewing. There was a company known as RI who were trialling various barcode methods of witnessing that were being used in some labs.


An article from the Guardian (UK) in 20021 says: "Although infertility treatment is miraculously clever, what it comes down to is that the right sperm and eggs are put together and the right embryos are put back," said Suzi Leather, the authority's chairwoman. "Embryologists are dealing with things so small you can hardly see them, so you have to ensure the right lab protocols are in place and are followed every time."

(you can read the whole article if you follow the link at the bottom of this blog)


After ‘human double witnessing’ became mandatory in Australia in 1998 and in the UK in 2002, many articles were published all around the world discussing the relative merits of witnessing procedures. Did they add value? How much time did they take? Did they reduce errors? Were there really enough errors to warrant all of the expense and extra time? And as such, witnessing of any sort took a while to catch on - through my own personal communication, I know that many clinics in the USA were not routinely using any witnessing procedures at all right up to 2007


After a while, people started to discuss witnessing in the context of a risk matrix - how likely was an event to happen, and how devastating were the outcomes if the event did happen?


Something like this:


We used Risk Matrices like this all the time when developing lab policies and had lists of what to do in adverse situations all over the lab - if the freezer failed, if the incubator alarm went off, if the power went out, if there was a flood, a fire, a bomb threat... anything you can think of, we thought about and had plans to manage!


It was generally decided that even though the likelihood of a mix-up occurring was remote, extremely remote or even extremely improbable - the outcome of any mix-up had the potential to be catastrophic. Catastrophic for the families concerned, but also for the embryologists involved.


Before long, witnessing was considered standard throughout Europe and Australia and most clinics in the USA were, at least in theory, on board.


But there were issues, and still a fair bit of room for error. An article in the (American) College of Reproductive Biology Newsletter from 20192 titled Witnessing in ART – Has the time come to utilize technology? states that:

The problems with the most common system of using another person to provide independent double check include:

  1. The witness may not be properly trained in the “Witnessing Procedure” particularly for embryologists working alone calling in a phlebotomist, receptionist or nurse to verify.

  2. The witness may be interrupted from their immediate task and provides only a cursory witness not an independent cognitive task.

  3. Who is the responsible person? The person providing the independent witness or the person completing the task asking for verification?

  4. Data from the nursing industry indicates that double witnessing does provide sufficient verification.

  5. Double checks depend of one fallible person assessing another fallible person’s work.

  6. Most laboratories do not have a detailed witnessing procedure. The procedures routinely say something to the effect of “. . . .verified by …..(another person). The details of how this witnessing occurs are rarely delineated. Who provides witnesses? How is that person trained in the witnessing process? How is that person summoned to witness? How is the witness documented? Does the procedure specifically say, “interrupt someone”? Who is the responsible person? The witness or the person completed the task? Does the procedure explicitly say what needs to be checked and how it is checked? Do I hold up a labeled tube of sperm and say this is John Doe and I am inseminating Jane Doe?

And this method of witnessing is even further complicated, particularly at insemination time, in couples where both partners do not have the same surname.

A fact sheet from Access Australia3 titled ‘How do I know that these are my embryos’ from 2013 quotes Dr James Catt:

The number of cross-checks that are used might seem to be excessive but this has been deliberately built in to the system to attempt to make it ‘fail-safe’. That is, if one set of required checks is missed or wrongly conducted then the next set should highlight this and correct it. Even with the best-designed systems in place there is always room for human error and sometimes this can occur. A couple of these errors have made headlines internationally whereby the procedures in IVF laboratories have been shown to be at fault.

So what happens now?

These days (2021) there are now a number of methods that can be used for identifying gametes (eggs, sperm and embryos) in the lab and allowing traceability throughout the procedures. We’ve already discussed Human Double Witnessing and its benefits and limitations, let’s look at barcode scanning.

This requires lab equipment to be labelled correctly and for the embryologist to ensure that they electronically scan all items as they take them into the critical work area (the bench or microscope area). Just like Human Double witnessing, this requires that the embryologist takes the steps necessary - offering up the tubes/dishes/pots to the scanner to be scanned, and ensuring that they hear the correct ‘beep’ to confirm that everything is correct. It’s possible, with barcode scanning and with human double witnessing, that OTHER items are also in the field - an extra tube, or dish that has not been scanned or witnessed that could inadvertently get caught up in the procedure and even, possibly, used by mistake. Whilst this risk is very small (virtually improbable) the severity of the outcome would be catastrophic.

The final option for witnessing is RFID technology. This system is automated and monitors an entire critical work area, meaning that anything taken into that critical area is automatically scanned - requiring no extra action from the embryologist. This means that when the embryologist is preparing a sperm sample for example - no other sperm samples can be on the bench. Or when eggs and sperm are being put together to attempt fertilisation, only the eggs and sperm from the couple being worked on at the time can be present.

It’s kind of like comparing the self-scanning checkouts at the supermarket with buying a handbag at Prada

The supermarket scanners require that you scan your goods, then weigh them to double check that you have scanned the correct item, plus there is a staff member present to keep an eye on things. But if you incorrectly scan something, and no one happens to notice - you can easily still walk out of the store.

Compared that to the handbags at Prada - they are fitted with an RFID tag that is disabled or removed when you purchase the bag. If you try to walk out of the store with an RFID labelled handbag, you can be sure there will be plenty of alarms!!

Around 65% of clinics in Australia are now using RFID technology and the rest are using a combination of the old Human Double witnessing, or barcode scanning technology.

Rest assured that in Australia and in the UK, we were ahead of the game with witnessing and it has been a part of our routine practice for over 20 years.


What’s your clinic using? Do you know?


Looking for more understanding of what goes on in an embryology lab? or some 1:1 guidance through a diagnosis of infertility? Read more about my services here: https://www.twolinesfertility.com.au/start-here




  1. https://www.theguardian.com/society/2002/nov/05/NHS.medicineandhealth

  2. https://www.aab.org/NewsBot.asp?MODE=VIEW&ID=554

  3. https://www.access.org.au/wp-content/uploads/2010/01/46-are-these-my-embryos.pdf

Further Information about RFID can be found here: https://fertility.coopersurgical.com/equipment/ri-witness/

also here: https://www.youtube.com/watch?v=zqbNmhxFack


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