Embryo management – low risk strategies
Human embryo culture is a complicated business, and nowhere in the IVF laboratory is the management of risk more important. This can be demonstrated by looking at data associated with laboratory processes for embryo culture and assessing the beneficial results.
Sometimes, even changing one item in a procedure can result in elimination of a sub-optimal practice. But staff must be motivated and believe in the change to perform it.
Let’s look at a three of instances of this:
Example A: incubator openings and risk associated logic
As good laboratory practice goes, it is important to ensure that there are enough incubators. This is important so that the culture conditions are not upset by regular opening of the incubators.
Data shows a large variation in incubator openings based on location in the laboratory and their position on the bench. Indeed, some preliminary research already indicates a direct link between pregnancy rates when incubators conditions are kept constant. This was based on fewer openings as less than 8 times as opposed to variable, which was more than 8 openings.
It is worth doing monitoring the number of times each incubator is opened to determine the number of incubators needed. A low risk management plan would entail not opening an incubator more than five times a day.
Planning in this way is known as risk associated logic and is a positive management process. The cost in this particular instance is also low. Because incubators, when the amortised over the lifetime of their use is relatively cheap.
Example B: moving and viewing embryos
As discussed in Part 2, risk is associated with moving and viewing embryos.
Risks include:
- Dropping the dish
- Over-cooling the dish
- Sub-optimal pH changes
- Changing the dish
- Changing the culture media
Good low risk management entails setting rules regarding the reasons for moving gametes and embryos. These should be clear in laboratory policy documents.
These rules can be ascertained and/or updated by interrogating current procedures:
- What movements of gametes or embryos are completely necessary and cannot be avoided? It may be possible identify certain stages that can be eliminated, along with the risks mentioned above.
- What are the scientific reasons for moving embryos? Every movement should be associated with a solid scientific reason. For instance, there is no need to remove an embryo form an incubator just to check on it on Day 2 or Day 4.
- Can we bundle movements of embryos? So that all movements and assessments of embryos are limited to when they are already being handled to change culture media formulations?
With this in mind it is a good idea to keep the culture system as simple as possible. You may want to assess using stage-specific media, as they require a Day 3 handling process that could be eliminated.
When handling, risk can be reduced by minimising the movement distance and using temperature and pH supporting equipment.
Example C: reduce heating time of media
Media can break down under prolonged heating releasing ammonia, which can harm the embryo. Therefore, it is a good idea to only use media that has a maximum equilibration time of 48 hours. However, many units presently equilibrate their blastocyst media dishes from the afternoon of Day 2. While the embryos themselves might only be in the media for 48 hours, the media itself will have been exposed for longer. The media will have been exposed for the 48 hours plus the equilibration time and this increases risk.
If pre-gassed culture oil is used as an overlay, then small (20 – 50 µL) droplets of culture media stabilise their pH rapidly. This means that dishes can be prepared, instead, on the day of use and can be ready after an hour.
There is evidence that combining these approaches not only significantly lowers risk but has a direct effect on productivity. One Australian clinic combined two risk management strategies. They reduced heating time and left the embryos alone on Day 2 and Day 4. This increased blastulation rates by 5% and utilisation rates increased from 35% to 46%.
So, risk management is not just about risk per se. It is also about the productivity that lies at the heart of the business model. And, as has been demonstrated, a low risk strategy does not have to be a high cost one! It does require thought, assessment and staff motivation and a commitment to the strategy of minimising risk.
Neil Madden, Editor
The Fertility Hub
