PGT-A

I will be undergoing IVF treatment. Should I have my embryo’s tested?

Like most things in medicine, this is not black and white!

The aim of testing embryos is to improve live birthrates by only transferring chromosomally normal embryos.  It should also result in a decrease in miscarriage rate.

The embryos potential to implant cannot be improved by the process of a biopsy. The improvement is per embryo transfer. If you compare a group of untested embryos with tested embryos, you would expect a higher pregnancy rate from a tested embryo because you have chosen to transfer a chromosomally normal embryo, whereas among the untested embryos it will be random which one is chosen for transfer.  You would not expect the cumulative pregnancy rate to differ, but it may take longer to achieve a livebirth with the untested embryos if many of them are abnormal.

We need to remember if we transfer an embryo there is a chance of pregnancy and if we elect not to transfer an embryo there is no chance of pregnancy.

Embryo biopsy cannot increase the cumulative livebirth rate because we are dealing with the same number of embryos, but we can potentially lower the cumulative pregnancy rate with PGT-A. Reasons why cumulative pregnancy may be lower include:

Damage to embryo from biopsy.

Incorrect result (false positive)- embryo not transferred that may have resulted in a live birth.

Mosaic embryo

Of these potential issues, the mosaic embryo is the main one we deal with when we get our biopsy results.

So what is a mosaic embryo?

A mosaic embryo is when some of the cells tested are chromosomally normal and some are chromosomally abnormal. We know many of these embryos can still result in a livebirth if transferred, but success is lower and miscarriage rate have been shown to be higher, compared to a chromosomally normal embryo.

The STAR study is the most useful recent Randomized control study to look into the benefit of PGT-A. The findings were that PGT-A did not improve overall pregnancy outcomes or decrease miscarriage rates per embryo transfer. There may be an improved ongoing pregnancy rate with PGT-A for women 35-40 years.

So should I have my embryos biopsied?

1. In discussion with your doctor looking at the recent evidence, the pros and cons, your history and beliefs, an informed choice can be made.

2. You may be more inclined to go ahead with testing if you end up with a large number of embryos for freezing.

3. You may prefer to test if you are >35 years of age

4. You may prefer to test if you have a history of unexplained miscarriages.