This technique consists of obtaining eggs, fertilizing them in the laboratory with sperm and then transferring the embryos to the uterus. In vitro fertilization (IVF) is advised when the fallopian tubes are damaged (tubal obstructions, tube-peritoneal adhesions, tubal surgeries); in cases of sperm disorders (mild to moderate male factor); in severe endometriosis; in cases of infertility without apparent cause; and when there have been previous failed inseminations.

To begin the procedure, different drugs are used to stimulate the ovary to produce the necessary number of eggs, without putting the woman’s health at risk. Through vaginal ultrasounds and measurements of hormones in the blood, it is possible to know when the eggs that are inside small cells in the ovaries (called Follicles) are mature. It is then that the eggs are extracted through a transvaginal ovarian puncture performed under ultrasound control in our operating room. This process lasts just 15 minutes and the woman receives gentle sedation so as not to suffer any discomfort. In two hours, she can return to her house. Meanwhile, in our laboratories equipped with the latest technology, the eggs are conditioned and the sperm sample is prepared using the recovery method that the sample requires. The eggs can be used immediately to fertilize sperm or frozen for future attempts. If you want to use them immediately, the eggs are placed together with sperm in a capsule for fertilization to occur. Fertilization occurs when the sperm enters the egg without help, by itself, and is evidenced in the laboratory when at 18 hours two pronuclei appear inside the egg, one corresponding to the nuclear material of the egg and the other to that of the sperm.

In the case of severe male factors, previous fertilization failures and presence of sperm agglutination, intracytoplasmic oocyte injection or ICSI is used in which a sperm is directly introduced into each egg. After about 18 hours, our fertilization experts examine the eggs to find out how many have been effectively fertilized or fertilized. They are left in culture conditions for a few more hours, during which the fertilized eggs begin to divide.

Depending on each particular clinical situation, the day on which the embryos will be transferred to the uterus will be decided. The CER recommends transferring no more than two good quality embryos in women under 35 years of age – to avoid high-risk hyper multiple pregnancies – and freezing the rest of the embryos for future use (see cryopreservation).

Embryo Transfer

The transfer of the embryos is carried out from 2, 3, 5 to 6 days after the eggs are extracted. Unless for some specific reason it must be deferred. It is a simple procedure that is performed under ultrasound control in an appropriate environment and does not require anesthesia. The patient can leave the hour. After 12 to 14 days it will be possible to know through a blood test of the beta subunit of chorionic gonadotropin (beta HCG) if the transfer has been completed.

The success of this technique depends on many factors, including the age of the woman, the quality of the eggs and sperm, among others. Naturally, young couples with no known history of infertility manage to get pregnant with a 20 to 25% chance per cycle, within the first year of unprotected sexual relations. New technologies have managed to greatly exceed these possibilities, reaching from 30% to 70% depending on age and technique applied.


The injection of a sperm directly into an egg, under a special microscope and through micromanipulation, has made it possible to obtain pregnancies that were once impossible. In 1992, a breakthrough was achieved in the field of assisted reproduction: sperm microinjection. In this way, many men with low quantity or low quality of sperm managed to become fathers without resorting to sperm donors. Virtually all men who have a reproductive problem in the ejaculate, in their testicles and other elements that participate in the production of semen) can have children. Sperm can be extracted from different parts of the male reproductive system. They must then be injected into eggs obtained through hormonal stimulation of the woman.