Over the passed few years there have been rapid tech developments in improving embryo selection and so increasing the chance of success of fertility treatment.
Patients often ask about the grade of their eggs directly after egg collection. The egg’s colour, shape and texture will be helpful, but it’s not until the fertilised egg (now called an embryo) has been allowed to grow for a few days can you really give any meaningful information about the quality of the embryo.
In the laboratory the embryologists keep a close watch on the embryos and are highly skilled in selecting the best embryos and advising the best day for transfer. The role of the embryologist cannot be underestimated. Although you may only meet them briefly, they are the key individuals in your treatment.
Traditionally embryologists select embryos based on the speed of how their cells divide, the number of cells, how much cell breakdown (fragmentation) there is and other more subtle markers of quality. Different labs use different grading schemes often using a combination of numbers and letters. Grading systems have changed over the years so it’s important to be careful when comparing embryos created in different clinics or even in the same clinic at different times.
Embryos that reach five days after fertilisation are called Blastocysts and may have a different grading system to those embryos that have not reached this stage.
Until very recently the daily routine in a laboratory is for the embryos to be removed from the incubator, moved to under a microscope where their appearance is checked before being returned to the incubator. It’s acknowledged that embryos prefer not to be moved around too much, so we try to avoid checking embryos too frequently. The majority of laboratories will still use this tried and tested approach.
There is obvious advantage to being able to continually monitor the embryos without disturbing them by moving them from one place to another and with the advent of faster computers and improved optics it is now possible to continually look at embryos in their incubator. Increasingly clinics are using time-lapse photography. This means that the embryo can be continually assessed but crucially without disturbing the embryo by taking it out of the incubator. There is a good YouTube video by the manufacturers of “Embryoscope” that is the most widely used time-lapse system in the UK. On top of this, precise embryo selection is improved using software that analyses the rate of progress from one developmental stage to the next.
But the real heart of the matter is not what the embryo looks like but being able to predict which embryo will go to produce a healthy on-going pregnancy.
It’s a huge disappointment for patients to have an unsuccessful cycle after they have been told that they have very high quality embryos based on their appearance, with or without the use of time-lapse techniques.
Time lapse is very helpful in identifying those embryos that look and develop in an expected way, but even top quality looking embryos will not always produce healthy pregnancies. In fact, some babies are born from embryos that don’t on inspection look top quality.
This means that an embryo’s appearance is not the whole story, or rather it’s not possible to completely judge an embryo by its appearance. An embryo that looks good on the outside may not be functioning well on the inside. For example. it may not have the normal amount of genetic information.
Pre-implantation Genetic Screening (PGS) technology is now a rapidly developing method of testing the embryos genetic information. PGS involves taking a cell from an embryo (biopsy) and assessing the genetic material. This allows selection to be made on the embryo genetics rather than embryo appearance.
It’s very much like reading through a few chapters of a book before buying, rather than deciding on how good it will be by looking at the front cover.
So if it’s such a good idea, why does everyone not use this technology? Large studies have still to show that it actually improves pregnancy rates. There is concern that embryo biopsy may damage the embryo affecting the outcome. The cost of biopsy continues to fall and is now less than a quarter of the cost of a total IVF cycle. Here is another good YouTube video to look at.
If you would like to discuss the different methods of embryo selection then please contact my PA Yvonne Baillie on 0207 125 0547 firstname.lastname@example.org to arrange an appointment.