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In Vitro Fertilisation comprises five steps: Ovarian stimulation, egg retrieval, fertilisation, culture and selection of embryos and embryo transfer.
Ovarian stimulation
By stimulating the ovaries, it is possible to control ovulation and the retrieval of several follicles. That is, we can obtain a greater number of eggs than in a normal menstrual cycle, in order to achieve a suitable number of embryos, thus increasing the possibility of pregnancy. During this process, which usually lasts between one week and ten days, the woman is supplied hormones to stimulate the growth of a greater number of eggs. In order to control that growth, tests and scans are carried out.
Egg retrieval
When the size of the follicles is right, a hormone is administered to produce a controlled ovulation. It is administered 36 hours before the egg retrieval. The retrieval is carried out in an operating theatre under sedation, using a special needle, which, through the vagina, collects the fluid contained in the follicles which, in turn, contain the eggs. In the lab, the eggs are separated from the fluid and placed in a culture medium inside an incubator. After one or two hours, the patient can go home.
Fertilisation
Once we have a sperm sample, it is processed to fertilise the eggs. On a culture plate, several micro-drops are prepared, where we will place the right concentration of sperm. Later, we place an egg in each of these micro-drops, and this way, within hours, one of the sperm will penetrate the egg, producing fertilisation. (This is In Vitro Fertilisation proper). This plate with the eggs and the sperm is left in the incubator, under conditions similar to physiological conditions, that is, 37º C, with a concentration of 6% of CO2 and high relative humidity (95%). 18-20 hours after insemination, we verify whether fertilisation has taken place, observing it under the microscope.
Culture and selection of embryos
The embryos formed (which are the eggs that were previously fertilised) will spend one or two more days in the incubator, where their evolution will be observed in order to determine their quality and be able to select the best embryos for their subsequent transfer.
Embryo transfer
After these days in the incubator, one, two or three embryos are transferred, depending on each specific case, medical advice and the wish of the patients. The total process takes no longer than half an hour. The embryos are introduced in the uterine cavity with a very fine cannula, guided by ultrasound, to place the embryos in the best place. We then wait for implantation to take place, to give way to pregnancy.