The transfer of a blastocyst embryo is an important stage in the in vitro fertilization process (IVF). Prior to the transfer, there is a lot that needs to happen. During an IVF cycle, a fertility specialist will combine the sperm and egg in a culture dish at a laboratory. If the fertilization is successful, an embryo will begin to develop. Typically, the embryo will be grown in culture in the lab until it reaches the blastocyst stage. Blastocyst stage occurs about 5 or 6 days after fertilization.
Unfortunately, not all fertilized eggs typically make it to blastocyst stage; some arrest in the lab. Some patients have blastocysts transferred fresh and others choose to have frozen embryo transfers. If you are interested in genetic testing like PGT-A to test for chromosome imbalances, you will likely need to plan for a frozen embryo transfer. After you have blastocysts made, you and your fertility doctor will need to make some decisions about your embryos. Here, we explore some of these questions so you know what to expect.
An overview of the decisions you’ll need to make about your embryos
A good fertility doctor will make sure that you feel involved and informed. During your IVF treatment, the doctor will discuss two key decisions you need to make in regard to your fertilized blastocyst embryos. These are:
- If there is more than one viable embryo, how many to transfer to your womb.
- Which embryos are the best quality and most likely to result in pregnancy.
It is important to remember that no matter how carefully the blastocyst embryo is selected, a good quality blastocyst does not guarantee a pregnancy. You can ask your clinic for success rates after an embryo transfer if you would like to know what your chances are. Once your doctor has discussed these issues with you and your partner, you will have a clearer picture of how your treatment is going to proceed. We’ll explain the details of these questions below.
How do doctors decide how many embryos to put back in the womb?
If more than one blastocyst embryo is available, most women will have one embryo transfer and freeze the rest for future use. This process is known as elective single embryo transfer or eSET. This reduces the chances of multiple births, which can cause complications. However, in some cases, the doctor may decide it is appropriate to transfer more than one embryo. This is usually the case for older women who are statistically less likely to have successful implantations.
How do specialists decide which blastocyst embryo is the best quality?
Embryos can vary in quality. As a result, your doctor will select the best quality embryo to transfer into your uterus. If there is more than one viable embryo, the embryologist will assess which embryo is the best quality. They will grade the morphology of the embryo by assessing how the blastocyst appears. In some rare cases, there may be no good quality embryos. In this scenario, the doctor will need to judge whether or not any of the embryos could result in a healthy pregnancy. The physician may recommend additional IVF cycles to attempt to create more embryos in this case.
Creating the best possible chances of a healthy pregnancy
At the blastocyst stage, the embryo is more developed, which means there is a great chance of implantation. However, every fertility journey is different. You, your doctor, and your embryologist will help you to decide whether or not a blastocyst embryo transfer is right for you. Together you will discuss your treatment in detail to ensure that you have the knowledge you need to feel comfortable throughout your treatment. From here, they will ensure that you are supported throughout the process, to offer the best chance of pregnancy.