Embryo Screening Procedure

Embryo screening can be used to check for certain abnormalities before embryos are transferred into the womb during IVF. The screening stage can be particularly important if you are at higher risk of these kinds of problems. It can ensure that you have the best chances of a healthy pregnancy after the embryo transfer.

What is the Embryo Screening Procedure?

The embryo screening procedure is a test that can be carried out during IVF treatment. It is performed after the eggs have been fertilised in the lab. The test can determine which of the embryos should be selected for transfer into the womb. Embryo screening for IVF may also be referred to as preimplantation genetic screening.

The main purpose of embryo screening is to check for chromosomal abnormalities. If an embryo has the incorrect number of chromosomes then it might not be able to develop properly after it is transferred into the womb. Other kinds of chromosomal abnormality can cause disorders that would affect the baby’s health and development. Chromosomal abnormalities are one of the most common reasons for embryos to fail to implant or to undergo an early miscarriage. This can happen with both naturally conceived pregnancies and embryos that have been produced using IVF.

Screening for these kinds of problems can ensure that your IVF treatment has the best chances of success. Embryos that have been selected through preimplantation screening have a 70% success rate for implantation and a successful pregnancy.

How Does Embryo Screening Work?

Embryo screening is one of the stages of IVF that takes place in vitro. The test is performed by taking a biopsy or sample of one or a few cells from the embryo, which at this stage is just a tiny ball of cells. The DNA from the sample can then be analysed to check for certain kinds of condition.

The most common embryo screening tests will check for chromosomal abnormalities. We usually have 23 pairs of chromosomes, but sometimes an embryo can be formed that has an extra or missing copy of one of the chromosomes. Chromosomal abnormalities like this are one of the most common causes of miscarriage. Even if the embryo is able to survive, it will have serious developmental abnormalities.

Other genetic screening tests can be performed to check for other kinds of problems, but these are usually only recommended if you are at higher risk. For example, if you have a family history of a condition such as Cystic Fibrosis then it is possible to screen the embryos for this.

Who is Embryo Screening for?

Embryo screening can be performed during IVF treatment. After the egg and sperm have been brought together in vitro, the embryo will be allowed to grow for a while before it is transferred into the womb. The embryos will be carefully assessed to ensure that the best quality ones are selected for the transfer. Embryo screening is one of the checks that can be performed at this stage of IVF treatment. It can detect embryos that are likely to have issues such as chromosomal abnormalities that could affect their development or survival.

You can decide which screening tests you want to have during your IVF treatment. You might want to have a genetic test for a specific condition if you are at higher risk, for example if you are older parents. Embryo screening is particularly recommended for parents who are over the age of 37 as the chance of chromosomal abnormalities increases with age. Other risk factors include having previous pregnancies that were affected by these kinds of abnormalities or a history of early miscarriages.

In some cases, couples who are at very high risk of genetic abnormalities may decide to have IVF in order to go through the embryo screening stage, even if they would have a good chance of conceiving naturally. For example, if the parents are carriers of a serious genetic condition, the embryo screening process can ensure that it won’t be passed on to the next generation.

The issues that are detected during embryo screening can cause serious developmental problems, lifelong health conditions or even miscarriages. Having the screening can, therefore, increase the chances of a successful, healthy pregnancy.

Is it Right for Me?

Genetic embryo screening isn’t required for IVF treatment, but it can help to increase the chances of success. You should discuss the options for preimplantation screening in detail with your fertility specialist before deciding if it is right for you. You might want to consider genetic screening if you:

    Are at higher risk of chromosomal abnormalities, for example due to being older parents or having a history of these disorders in previous pregnancies
  • Have a history of early miscarriages which might have been caused by chromosomal abnormalities
  • Are affected by or carrying a genetic disorder that could be passed on to your baby

However, this can be a very personal decision. You might decide that you prefer not to screen the embryos if you are at lower risk of chromosomal abnormalities or you aren’t worried about passing a genetic condition on to your child.


The fertility specialists who are performing your IVF treatment will use the results of the screening to select the healthiest embryos for transfer. You will be informed of the number of healthy embryos that have been produced.

In most cases, only a single embryo will need to be transferred into the womb for each cycle of IVF. You may decide to freeze any remaining embryos for use in future cycles of IVF. Alternatively, they can be disposed of or donated for training, research or to another couple.

The embryos used for IVF will always be checked to ensure they appear as healthy as possible. Only embryos that are developing as expected will be transferred into the womb. However, preimplantation genetic screening can provide additional information about the embryos that can reduce the risk of developmental disorders and miscarriage. It can therefore increase the success rate for IVF.

How Can We Help?

Embryo screening can increase the chances of success with IVF treatment, so it can be a very important step, especially if you are at higher risk of abnormalities. We can advise you on your options for embryo screening in the UK and overseas. We can arrange the tests that you need and help you to understand what the results mean.

If you have questions about embryo screening or you want to arrange genetic tests during your IVF treatment then contact us to get personalised advice from an experienced fertility specialist. Preimplantation genetic screening can check for hundreds of different conditions as well as for chromosomal abnormalities, so it is important to get expert advise on which tests are appropriate for you.

Embryo Screening Procedure FAQs

Embryo screening involves taking some of the cells from the embryo and testing them for certain chromosomal abnormalities or genetic conditions. It is possible to screen for specific diseases or to count the number of chromosomes that are present. The test works because the early embryo can still develop normally even if some of the cells are removed. It can ensure that the healthiest embryos are selected for transfer, which can increase the chances of implantation and a successful pregnancy.

Embryo screening can be performed to check for specific genetic conditions that run in your family or to ensure that the healthiest embryos are selected for transfer. It can check for chromosomal abnormalities that might prevent the embryo from implanting and developing normally. Embryos that have passed the screening process are more likely to result in a successful pregnancy.

Screening embryos for genetic or chromosomal abnormalities can increase the success rate for embryo transfer. About 70% of embryos chosen after screening will implant successfully. Screening also ensures that only the healthiest embryos are transferred, so it can reduce the risk of developmental disorders and miscarriage.

Embryo screening is performed on the embryos in vitro, while they are still at a very early stage of development. There are no extra risks for the mother as the tests occur outside of her body. Although cells are removed from the embryo for testing, this won’t affect their development if they are selected for transfer. At this early stage, embryos still have the ability to split to produce identical twins, so they can still develop normally even if some of the cells are lost.

The screening process is very safe for the embryo. There is no evidence of any health risks to babies who are born after preimplantation screening. However, there is a small chance that some of the embryos could be damaged when the cells are removed for testing. Any damaged embryos won’t be suitable for transfer so they will have to be discarded. This means that there is a small chance that none of the embryos will survive the screening process. You might decide that it is better not to take this risk, especially if the IVF procedure was only able to produce a small number of embryos.

Embryo screening is performed during the IVF process after the embryos have been created in vitro. The embryos are allowed to develop up to the 6 to 8 cell stage. One or two cells can then be removed from the embryo for analysis, leaving the rest of the cells intact. The remaining cells will be able to replace the missing cells and the embryo will develop normally if it is selected for transfer. Screening can also be performed on frozen embryos before they are used for transfer.

It is important to be aware of the limitations of genetic screening. The tests can’t detect all possible genetic disorders and there is a small chance that the results could be wrong. A healthy embryo might incorrectly be identified as at risk, while an embryo with a genetic disorder could appear to be healthy and selected for transfer. There is also a chance that none of the embryos will be normal and suitable for transfer.

Genetic screening can identify embryos that have the wrong number of chromosomes. This includes chromosomal abnormalities that cause disorders like Downs syndrome as well as those that can make the embryo inviable. Testing is also available for many hereditary conditions for which the genes have been identified, including cystic fibrosis, Huntingdon’s disease and muscular dystrophy. More than 600 different conditions can be screened for during preimplantation testing if necessary. However, there are still many conditions that can’t be screened for because the genes associated with them are not yet understood.

Embryo screening should never be performed to choose the baby’s sex for personal or social reasons. Chromosomal abnormalities affecting the sex chromosomes can be screened for and the procedure can be performed to check for embryos carrying genetic disorders on the sex chromosomes.

The fertility specialist who is providing your treatment will be able to provide personalised advice on embryo screening. You might also want to talk to a genetic counsellor, who can help you to understand the conditions that are being screened for and what the results mean. This can be particularly helpful if you are affected by a genetic disorder or if you are a carrier for a specific condition.

If you decide not to have preimplantation screening then it is still possible to detect some chromosomal abnormalities or genetic disorders later on if you become pregnant. Ultrasound scans, Non Invasive Prenatal Testing (NIPT), amniocentesis and chorionic villus sampling (CVS) can all help to screen for these kinds of conditions. However, these tests can only be carried out later in the pregnancy. Preimplantation screening is performed before you get pregnant.

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