Oocyte donation

ovuloOocyte donation (egg donation) is a treatment that involves using eggs from a donor. The next step entails either a synchronised treatment, meaning the donor and recipient are medicated in parallel to match the timing of egg retrieval and embryo transfer, or the use of vitrified donated eggs, which obviates the need for simultaneous treatment.

Treatment protocol for egg recipients

In this case, the aim of the treatment is solely to prepare the endometrium to be receptive to the arrival of an embryo. The aim is to simulate a ‘standard’ female ovarian cycle by administering the hormones that are normally produced in the ovary during a natural cycle.

Oestrogen and progesterone are administered sequentially according to the following schedule:

1 - Patients with preserved cycles

ovulo2In patients with preserved cycles, pituitary suppression with aGnRH (Gonapeptyl, Decapeptyl, Synarel or Procrin) is initiated around the 22nd day of the cycle or on the 1st day of the cycle in the case of a short protocol.

About 10 days later, usually coinciding with menstruation, an ultrasound scan is performed to check that the cycle is functioning correctly and to rule out the appearance of functional cysts or endometrial polyps that could alter the correct preparation and receptivity of the endometrium.

Oestrogen replacement therapy with oral oestradiol valerate is then initiated. The specialist will advise the patient on gradually increasing the dose.

After two weeks, an ultrasound scan is performed to measure the thickness of the endometrium and determine the level of oestradiol in the blood to check for proper oestrogen impregnation. The dose will be adjusted if necessary. This treatment can be maintained for around two months while waiting for the egg donor, who has simultaneously begun her ovulation stimulation, to successfully complete her treatment.

If the donor is being synchronised or when working with vitrified eggs, the recipient's partner is asked to come in to provide a semen sample so that the eggs can be fertilised. Alternatively, a semen sample that has been cryopreserved for this purpose is used, and the recipient is given progesterone (the specialist will inform her of the dose and when to take it). This treatment will continue until the day of the pregnancy test.

Embryo transfer will take place between 3 and 5 days after fertilisation.

2 - Patients without cycles

In the case of patients without cycles, endometrial preparation treatment begins directly with oestrogen in the dosage and at the times specified by the specialist. After 15 days, an ultrasound scan is performed and the blood oestradiol level is determined. Progesterone is then added, which the patient must take in the doses recommended by the specialist.

If the donor is being synchronised or when working with vitrified eggs, the recipient's partner is asked to come in to provide a semen sample so that the eggs can be fertilised. In addition, the recipient patient must take progesterone in the doses recommended by the specialist.

Embryo transfer will take place between 3 and 5 days later.

After fertilisation, the embryos are monitored in the laboratory. They are supervised by biologists and monitored to ensure their proper development in the initial stages. They are kept in incubators at a constant temperature in culture media suitable for their proper development.

Between two and three days later, they are evaluated and selected for transfer to the patient and/or vitrification. Not all of them develop correctly, so some will interrupt their development and be discarded for transfer.

In certain situations, it is considered suitable to cultivate embryos for a longer period, reaching the 'blastocyst' stage, a more mature form, before their transfer on the fifth or sixth day of development.