Assisted Fertilization
Pregnancy and Fertility treatments

During the natural process of ovulation, FSH hormone triggers the growth of several oocytes inside their respective follicles. Only one of the oocytes will become ready to leave the follicle and attach to the uterus, the rest will die.
Assisted fertilization treatments seek to increase the chances of successful pregnancies by stimulating the ovary with extra hormone and making it produce more than one oocyte. The woman is injected the same hormone that induces the natural development of follicles, but in higher doses, allowing many of the follicles that would have otherwise died due to the growth of a dominant follicle to continue their development. This hormone is injected daily with a syringe and it is such a simple procedure that the patient can do it by herself.
The development of the follicles induced by stimulation is monitored with transvaginal echography. Due to the fact that the production of follicles varies according to each woman, the physician will adjust the doses according to each case.

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Once the follicles have matured, the oocytes growing inside each one of them will be collected. The woman is sedated and receives local anesthetics to avoid any kind of discomfort. A cardiologist supervises her vital signs while the physician performs the transvaginal echo-guided punction of the follicles. The oocytes are extracted from the follicles by suction, using a hollow needle. The number of oocytes extracted will vary according to each woman.

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The semen belonging to the woman's partner is examined in order to establish its quality. When there is not enough sperm in the semen, it becomes necessary to perform a testicular biopsy or puncture to collect them. Once the amount and quality of the sperm is considered adequate, the in vitro fertilization procedure begins.

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When the quality of the sperm is good, they are incubated together with the oocytes in a propitious medium where fertilization will take place without external help.
But when the quality of the sperm is not good enough or when they are too few, the physician must resort to a special technique that will help the sperm penetrate the oocyte. This technique is called ICSI (Intra Cytoplasmic Sperm Injection), it consists in injecting the sperm directly inside the oocyte. Thanks to this technique, fertilization can take place even when the sperm is too weak.
Twenty four hours after in vitro fertilization or ICSI, the oocytes are examined to see if the first signs of fertilization are already visible, that is, two small spheres inside the oocyte: the male and female pronucleus.

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Once the pronucleus become visible, the embryos are incubated during one or two days more to monitor cell division: first they divide into two cells, then into four. The embryos that have divided into 8 cells 72 hours after they were collected will have better chances of attaching to the uterus. Sometimes, the embryos are placed in another special medium and left for a few days more until they reach the blastocyst stage, when they are fit for implantation in the uterus.
Sometimes, the embryo's quality is not good enough because the pellucid zone that covers them is too thick. If the pellucid zone is too thick, the embryo will not be able to break through it and attach to the uterus. When this occurs, a small hole is made in the pellucid zone to help the embryo break through; this is called 'assisted hatching'.
The chosen embryos are transferred to the uterus by means of a cannula. This procedure is VERY simple and it does not require anesthesia, it is monitored by echography so that the embryos will be placed properly.

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Two or three embryos are usually transferred. The number of embryos that will be transferred is decided according to the woman's age, the characteristics of the embryos and the couple's background. This allows for better chances of achieving successful pregnancies and lower probabilities of multiple pregnancies.
When the number of embryos exceeds the number that will be transferred, they may be preserved for future pregnancies so there will be no need to repeat the previous stages.

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Once the embryo has been transferred, the woman may return to her usual activities. She will only have to take progesterone, the hormone that helps the endometrium's development, where the embryo will attach.
Approximately 14 days after the embryos has been transferred, a test will be carried out to see if she really is pregnant. Two weeks later, an echography will be made in order to see if the gestation sack has developed and so as to check the heart's activity.
Once the pregnancy has been confirmed, the future mother will have to take care of herself like every other pregnant woman.

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