Do you know in vitro fertilization?

This technique is indicated in couples with sterility for a obstruction in , in cases of male factor, endometriosis, some cases of ovulation disorders and in some cases of sterility of unknown origin and artificial insemination failures.

Phases of in vitro fertilization

The first phase of the technique is the induction of ovulation. This treatment tries to stimulate the ovaries to cause the growth of several follicles at the same time and therefore obtain greater number of oocytes, given that not all oocytes can be fertilized nor all those that are fertilized will develop into embryos. The treatment usually lasts between 10-12 days and requires ultrasound controls to control the number and growth rate of the follicles and analytical controls to assess the estradiol, a hormone that will increase as the follicles mature. There are two different treatment guidelines, the long and the short guideline. The long regimen begins in the second half of the cycle with a nasal or subcutaneous treatment that inhibits natural hormonal control to prevent ovulation at an inappropriate time of treatment.

Injections to induce ovulation

Later the ovulation induction with subcutaneous injections. The short protocol directly initiates ovulation induction. When the follicles are mature, a dose of HCG is administered, a hormone that will cause ovulation after about 36 hours. 10-15% of IVF cycles are canceled due to a poor response to treatment, generally due to not achieving an optimal number of follicles, other times due to irregular hormonal levels or early ovulation.

Just before ovulation occurs, the follicular puncture, which consists of a simple surgical intervention, lasting about 10-15 minutes and performed in the operating room under sedation. The oocytes are obtained by ultrasound-guided transvaginal puncture, and with an ultrasound control the vaginal fornices are punctured and each follicle is aspirated with a fine needle.

Classification of oocytes in the laboratory

The fluid obtained and containing the oocytes is transported to the laboratory in sterile tubes. There the embryologist will observe the oocytes, will classify according to their maturity and distribute them in culture plates suitable that will be placed in the incubator at 37ºC. The time that must remain in culture varies according to the degree of maturity of each oocyte, and if some of them are too immature or not suitable for insemination, they are discarded. The couple is informed of the number of oocytes retrieved, which does not always coincide with the number of follicles observed in the control ultrasound scans.

The semen sample

On the same day as the follicular puncture, the sample of , which must be collected according to some simple rules: prior sexual abstinence of 3-5 days, antibiotic treatment to avoid possible contamination, obtaining the sample by masturbation and collection in a sterile container. The sample will be processed in the laboratory by a density gradient technique to select the most valid sperm. In cases where a semen sample from the partner cannot be used, a semen bank sample can be used.

The timing of insemination

After the follicular puncture and obtaining the semen sample, the insemination. Conventional insemination consists of putting the oocyte in contact with a certain concentration of sperm, 100,000 per oocyte in a culture dish. These plates are kept at 37ºC, in suitable humidity and gassing conditions.

At 17-20 hours after insemination it is checked whether the fertilization. Correctly fertilized oocytes have two pronuclei, each containing the genetic information of the male and female sex cell. Unfertilized oocytes or other abnormally fertilized oocytes can also be observed. The fertilization rate is around 70%. Fertilization failure must be analyzed in the face of new assisted reproduction treatments, since there may be male factors, oocyte factor or both, and it must be studied before performing new treatments.

The fertilized oocytes they are observed daily to assess their development. At 12-14 hours post fertilization, the first cell divisions begin. The embryos are classified according to their characteristics morphological and according to the rhythm of cell divisions, those of good quality will reach 4 cells on the second day of culture and 8 on the third day of culture. Cases in which cell divisions are not symmetrical or cell fragmentation is present require a more detailed evaluation and in vitro culture to the blastocyst stage may be indicated on the fifth day of culture.

Embryo transfer

Embryo transfer is the process of placing embryos in the mother's uterus. The number of embryos transferred it is variable, and depends on several factors. It must be a consensual decision between the doctor and the couple, always within a maximum allowed by law of three embryos transferred. This process is carried out in the operating room, but as it is not painful it does not require anesthesia, a very fine cannula is inserted through the neck of the womb and the embryos with culture medium are introduced through it. The patient should remain between 15 and 30 minutes of rest subsequently. Depending on the quality of the embryos, embryo transfer can be carried out on day 2-3 of culture, when the embryos present 4 cells or on day 5 of culture in the blastocyst stage.

And now?

After embryo transfer it is recommended rest for a few hours. The following days you should lead a quiet life, avoid physical exertion, sports and sitz baths, and not have sexual intercourse. The indicated treatment should be followed, which is usually progesterone in vaginal ovules that will be kept for a few weeks if pregnancy is achieved and if not until the appearance of the rule. In some cases, treatment is also indicated in estrogen patches or pills.

In case of no earlier menstruation, 14 days after follicular function a tests to find out if pregnancy has occurred. If it is not possible to perform it, a pharmacy urine pregnancy test can be done on the 16th day after the puncture. The percentage of pregnancies achieved is round 45-50%, but with a very important variability according to the characteristics of each couple (age, cause of infertility, previous pregnancies ...)

The gestation achieved by in vitro fertilization, has no more risk of complications than a natural pregnancy. The miscarriage rate depends a lot on the age of the woman, but is around 15%. An increase in the rate of malformations or chromosomal alterations has not been detected in these pregnancies. The risk of ectopic pregnancy is 2-3%, despite having placed the embryos within the womb.