Embryo transfer, implantation window and fresh cycle donor egg program – is it complicated to synchronize the cycles?

Oocyte donation, embryo transfer, implantation window and synchronization. It’s a lot and yet not everything crucial for the successful result of IVF treatment.

Regardless of whether you’re at the beginning of the IVF process or after a few attempts you want to know how it all works, especially that it is a highly complicated matter. For doctors, it’s just well-established approach in assisted reproductive techniques, for you a lot of uncertainty. That’s why our experts explain each step along the way.

Watch answers from:
Dr Juan Carlos Castillo, Instituto Bernabeu,
Dr Esther Marban, Clinica Tambre, Spain
Dr Maria Arque, Fertty International, Spain

Fresh embryo transfer – how complicated is it to synchronize the cycles of the donor and recipient?

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Please find 3 answers recorded with 3 IVF experts below.


Dr. Juan Carlos Castillo, Instituto Bernabeu, Spain

Answer from Dr. Castillo

Well, let me tell you that all oocyte donation cycles are a well-established approach in assisted reproductive techniques. Oocyte donation cycles give us the unique opportunity to treat patients with or without ovarian function. In patients without ovarian function—this means having a premature ovarian failure or even menopause—previous artificial endometrium preparation is mandatory before proceeding to oocyte donation. Endometrium preparation involves the sequential use of two hormones: estrogen and progesteron. The role of using estrogen is to promote the thickness of the endometrium and this hormone can be provided via several routes. It can be administered orally, transdermally or vaginally. After the endometrium has been primed with estrogen, a second hormone must be added—progesteron—which can also be administered in several ways. For example, we have the vaginal route which is the most frequent method, especially here in Europe. It can also be given orally, subcutaneously or via an inter-muscular route of administration. In patients with active ovarial function, the best approach is to first of all induce a blockage of the ovarian function by using mediation called a gonadotropin-releasing hormone agonist in order to render the patients functionally agonad—this means inducing a transient period of pharmacological menopause. The goal of doing this is to circumvent the cycle of synchrony between the donor and recipient. Afterwards, we may continue with the endometrium preparation in the same way as with a patient without ovarian function


Dr. Esther Marban, Clinica Tambre, Spain

Answer from Dr. Marban

We do it daily. We try to synchronise patients and donors day by day, so we can do it in different ways. One of them is by using the contraceptive pill. The patient and the donor can take it and then stop taking it at the same moment, and their periods will start more or less on the same day, and they will go through the cycles in parallel. Apart from that, we can also use an injection called Decapeptyl, which the patient is going to use in a certain moment of their cycle – when they start endometrium preparation, the endometrium is going to wait until the donor starts the cycle and we have the eggs. We can use both of these methods so they can be synchronised as we need.


Dr. Maria Arque, Fertty International, Spain

Answer from Dr. Arque

In order to synchronise the cycles for an egg donor and recipient, they usually have to take the oral contraceptive pill for a few weeks, because that way, we can get them both to have their period at the same time. Once they both stop the pill, they are going to have their period between two and four days after, and what is going to happen next is that the egg donor will begin the egg stimulation treatment to make the eggs grow and the recipient will undergo endometrial preparation. Around ten to twelve days after, the egg donor is going to be ready for the egg collection and the endometrium of the woman who is going to receive the eggs is going to be ready as well. What is going to happen then is, on the day of the egg collection, the eggs are going to be fertilised with the sperm and the woman who is going to receive the embryos is going to start progesterone treatment as well, and five days later, she will undergo the embryo transfer. Obviously, it is a little more difficult to synchronise the cycles when we are using fresh eggs, but it is possible, and we need to take into consideration that there is a very small risk of cancellation because of unexpected events during the cycle, such as the donor not responding to the cycle as we were expecting, or the endometrium not responding as we were expecting and we have reschedule.


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