In this webinar session, Dr Jana Voborská Neudeckerová, IVF Specialist at Unica Clinic, discussed single embryo transfer and whether it is always the best option.
Dr Neudeckerová started by explaining the whole embryo transfer process in IVF process treatment. She also answered the question that is so often asked by patients: Is single embryo transfer always the best solution?
IVF process starts with the stimulation of the ovaries, which is done with FSH hormones and these hormones a woman needs to inject herself, and it starts on the second day of the menstruation bleeding. On about the 7th or 8th day of a period, an ultrasound checkup is performed to check how many follicles are growing, and how big they are. According to this ultrasound, it’s possible to plan an egg retrieval. It is a short surgical procedure under general anaesthesia, during this procedure the ovaries are punctured, the follicle fluids are taken, and in the follicle fluids, the embryologists will find matured eggs, and only those will be fertilized. After 5 days of embryo development, at the blastocyst stage, embryo transfer is performed.
The embryo transfer procedure is simple, painless, and takes about 5 minutes. It is one of the key steps in the IVF process. During this procedure, the embryo is inserted into the uterine cavity with ultrasound to be sure that the catheter is inside the uterus, the embryo will be put correctly, and after 2 weeks, the woman will do the pregnancy test, and hopefully, with a positive result. This is how it works in a fresh transfer.
However, if it’s not the first transfer and we have to do a frozen embryo transfer, no needles or injections are needed, and oral or vaginal tablets of oestrogens and progesterone are used for the transfer. At the beginning of the cycle, we start with using oral oestrogens, around the second day of the period, we will do the ultrasound checkup of the endometrium, and if the endometrium is in optimal condition and is trilaminar and if it is about 7 or more millimetres high, then we can plan the embryo transfer.
The first division of the embryo occurs on day 3 of embryo development (morula stage), but at this stage, it is still too early to determine the potential of this embryo to implant. Many of the embryos on day 3 may be of similar quality, and that is why it is difficult to see which ones are the most promising. Therefore, it is better to allow the embryos to develop further and observe which embryos can reach the blastocyst stage. The embryo transfer of blastocyst, day 5 of the development, has the best potential.
The number of embryos to transfer
It’s possible to transfer 1 or 2 embryos. Double embryo transfer doesn’t double the chance of pregnancy, the chance is higher, and if you transfer 2 embryos, there is a high risk of multiple pregnancies. These can cause a higher risk of miscarriage. Recent studies suggest that sometimes when one embryo is healthy and the second embryo has some, for example, genetic issues, it could influence the other embryo and cause a miscarriage. Endometrium behaves differently toward healthy and unhealthy embryos. Other risks involve preterm birth and low birth weight, also, pre-eclampsia, higher blood pressure, and intrauterine growth restriction of the fetus. Therefore, experts recommend transferring just one embryo at a time.
Studies regarding single embryo transfer show that after a single embryo transfer, the chance of live birth is 33%, if you do a double embryo transfer, it’s higher, it’s 46%. However, if we look at multiple pregnancy outcomes, in single embryo transfer, it’s 16%, while in double transfer, it is almost 17%, and the chance of pre-term birth with double embryo transfer is quite high, it is 31%. The risk of low birth weight is also nearly 30%. These are the reasons why single embryo transfer is recommended.
EmbryoGlue -is a special medium designed to transfer embryos directly to the uterus. It gives a higher chance of implantation, it increases the chance of pregnancy by about 4-5%.
PGT-A (Preimplantation Genetic Testing for Aneuploidies), and PGT-M (Preimplantation Genetic Testing for Monogenic disorders), its genetic examinations of the embryo before embryo transfer, it’s possible to do it only in the blastocyst stage of development. The embryologist takes around 10 cells of the embryo, sends the sample to the genetic lab, and the embryos are checked to see if there are any abnormalities in the number of chromosomes. PGT-A doesn’t check for specific genetic diagnoses. PGT-M testing is done to evaluate the embryos for genetic disorders before implantation, and has been designed for individuals who know they are at an increased risk of having a child with a specific genetic disorder.
Embryoscope is another tool that can be used that allows the embryologist to see the embryos by microscope 24 hours continuously, so they can see their de development, they are monitored, and it helps to recognize and identify healthy embryos.