Fertilization in vitro - Sperm microinjection

Zigoto

Ovocito maduro

Microinyección

Embrión

I. Information about the treatment

What happens during the in vitro fertilization?
During the “in Vitro” Fertilization (IVF) the feminine gametes are fertilized outside of the woman’s body. For this the ova are obtained from the woman’s body and in the laboratory they are put together with the spermatozoon of the man.

Once the ova are fecundated, a limited number of complete embryos (maximum of 3) are transferred into the uterus of the woman, so that they could continue to develop there in a natural way.

When is it advisable?
— Unknown cause of infertility or sterility.
— Absence or damage in the fallopian tube.
— Decrease in number, activity and abnormality of the spermatozoa.
— Endometritis, which is an abnormal growth of tissue in the abdomen that normally covers the internal walls of the uterus.
— Ovulatory disorder.
— Immunological disorder.
— Other.

In general, IVF procedure is realized after having “blocked” pharmacologicaly the natural cycle of a woman and having stimulated her ovaries through a hormonal treatment in order to stimulate the development of multiple follicles. To follow up the progress of this treatment, ultrasonography and hormone tests are carried out.

— The ova are extracted from the ovaries of the woman by paracentesis of the follicle. This intervention is controlled through ultrasonography and always done under anaesthesia. Following this, the ova are prepared and classified in the laboratory. In exceptional cases it can happen that no ovum is obtained during the procedure.

— The semen is prepared in the laboratory to eliminate certain components and to select the most adequate spermatozoa for the fecundation.

  The ova are inseminated (with the spermatozoa) through conventional in vitro fertilization or by sperm microinjection.:

— In the conventional in vitro fertilization (IVF), the spermatozoa and the ova are incubated together for a few hours.
— In the method of sperm microinjection (ICSI), a previously selected and immobilized spermatozoon is placed into the cytoplasm of the mature ovum (M II)

The rate of fecundation can fluctuate according to the cases, but on the average, it is 65-70%.

After the fecundation took place, it’s decided through observing the first embryonary divisions that, depending on the case, in which number and state (cellule/zygote) the embryos should be transferred into the woman’s uterus. It’s recommended to transfer two embryos, although the maximum number is three (Act 14/2006). Approximately in 8% of the cases the transfer of embryos cannot be accomplished due to failure of fecundation (3%) or no not being able to obtain embryos apt for transfer (5%).

The remaining embryos in good quality (not transferred into the uterus) are cryopreserved and stored in the embryo bank for later their use.

The woman continues to receive a hormonal treatment in order to encourage the vitality of a possible pregnancy.

to the top      

II. Complementary treatments

II.a. Defrost of embyos


What does consist of?
The control and preparation of the uterus of the woman with the aim of achieving its ideal condition for receiving the embryos, so that the embryos could continue their natural development there.

When is it advisable?
When cryopreserved embryos are available from an earlier IVF cycle.

Procedure
Although sometimes it’ possible to realize the transfer during the natural cycle of a woman, in most of the cases it’s necessary to put through the uterus a supplementary hormonal treatment that is controlled by ultrasonography and blood test. Once the date is named, the requested number of embryos, according to the availability of course, are defrosted and if it’s possible, they are implanted into the uterus of the woman so that they could continue their natural development there.

It’s possible that in spite of the preparation of the cycle, the woman does not achieve the desired conditions for the embryo transfer and therefore it’s advisable to initiate a new treatment.
Another possible reason for the embryo transfer eventually not taking place is the fact that approximately 40-50% of the crypreserved embryos do not survive the freezing-defrosting process.

to the top      

II.b Assisted hatching (AHA)

The hatching or assisted eclosion is a method during which an aperture is made on the pellicular zone (external membrane) of the embryo before its transfer to the uterine. Of course this intervention does not endanger the vitality of the embryo.

It’s demonstrated by numerous studies that making an aperture in the pellicular zone of all the embryos before their implantation into the endometrum of the uterus, can encourage the hatching or eclosion. These results suggest that in certain cases the application of this method can cause a significant increase in the rate of implantation and pregnancy.

The method of hatching, with or without moving away fragments of the cytoplasm, can be adopted only in case the medical-biological team considers it appropriate, and after that the necessary microscopical examination of embryos and the evaluation of the case took place.

to the top