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In Vitro Fertilisation (IVF) and embryo cultivation

When was In Vitro Fertilisation discovered?

In 1978 the first human gestation through In Vitro Fertilisation (IVF) was performed by the British team of doctors Edwards, Steptow and collaborators. This technique culminated with the birth of Louis Brown, known as the first "test tube baby.” Since then, the IVF techniques have evolved considerably and have been applied in the majority of developed countries.

What is In Vitro Fertilisation?

In Vitro Fertilisation is under what is considered as Assisted Reproduction Techniques. Particularly, In Vitro Fertilisation consists in imitating the fertilisation process in a laboratory just as it occurs naturally. The aim is to achieve embryos from the woman's (ovums) and man's (sperm) gametes. Once the embryos are obtained in the laboratory, they are deposited in the maternal uterus, a process known as "embryo transfer." The proper lab conditions are very important when carrying out this technique, along with the personnel's training.
Within In Vitro Fertilisation there are two techniques: conventional in vitro fertilisation (IVF) and Intracytoplasmic Sperm Injection (ICSI).



 
 


Punción de Ovocitos








 
IVF

Who is conventional IVF for?

In theory, IVF was used as a sterility treatment for women with tube obstruction, which physically impedes pregnancy since sperm can not reach the ovums for fertilisation. However, nowadays there are many more indications such as for specific cases of bad quality semen (not serious), failure in artificial insemination procedures, ovary dysfunction, endometriosis, sterility for unknown reasons, etc.

How is it performed?

First the right number of ovums and sperm must be obtained. In order to obtain the right number of ovums the patient must be submitted to an ovum induction procedure. With this treatment we obtain various ovums in the proper state of maturity in order to be inseminated in the lab with the partner's semen. The ovary follicles, which contain the ovums, are directly suctioned from the ovaries in an intervention known as "transvaginal ultrasound-guided puncture.” This is a fast out-patient intervention. The patient is sedated (with a mild anaesthesia) and does not feel any pain. During the intervention, which usually lasts 15 minutes, the follicles are suctioned through the vagina without any type of surgery. The ovums are processed in the lab where they are put in contact with the semen. Previous to this, the semen sample must be treated in a process known as “sperm boosting” with the aim of separating the most fertile sample. The day after the IVF, the percentage of ovocytes fertilized by the sperm is evaluated.

How and when should we obtain the semen sample for the IVF?

The semen sample collection and transportation to the lab is vital both for processing and for obtaining the desired results.

The semen sample must be received at the lab the same day as the follicular puncture before 12:00 and must fulfil the following specifications:

- No sexual relations 3 to 5 days prior to the obtaining the sample.
- The semen must be obtained from masturbation.
- Only use the suited recipient (urine collection jar).
- The quality of the semen depends on the quality of the orgasm. Therefore, the necessary amount of time and stimulation should be taken.
- Collect all the semen from ejaculation and close the container well.
- Deliver the sample to the lab within an hour from collecting the sample. The sample must be protected from light, cold or excessive heat.

ICSI


What is ICSI?

ICSI is the initial for Intracytoplasmic Sperm Injection. The technique consists of injecting a single sperm into the ovum to fertilise it. This procedure is under the framework of techniques known as micromanipulation which require a great expertise from the biologist.

Who is conventional ICSI for?

ICSI first started in Belgium in 1992 by Palermo and collaborators as a technique to solve fertility problems in men with very low quality semen samples and who could not fertilise though conventional IVF. With this technique we can fertilise the ovocytes even with more serious cases where the sperm is obtained through a biopsy of the testicular tissue.

How is it performed?

Obtaining the ovums is done in the same way as with conventional IVF. The semen sample is prepared in the lab with the hope of obtaining the part of the semen with the highest quality. The complete procedure is done under the microscope where the sperm is selected individually. Once selected, the sperm is microinjected within the ovum with a microtube.

How and when should we obtain the semen sample for the IVF?

The general specifications for obtaining the semen sample as described in IVF. However, as previously stated, sometimes there is no sperm in the ejaculation (azoospermia) or some pathologies coincide with the male forcing us to obtain sperm directly from the testicle through interventions known as "testicular biopsy.” This intervention is performed with local anaesthesia and consists of extracting a small amount of testicular tissue through a small incision in the testicle. This tissue sample is processed in the lab with the aim of separating the sperm found inside. These sperm will be used for the microinjection. The biopsy is scheduled by the medical team and synchronized with the woman's treatment as close as possible. There is also the possibility of freezing the sample obtained in the biopsy in order to use it later in ICSI cycles (sperm freezing).


After conventional IVF or ICSI, the ovums are cultivated in special incubators that hold the proper light, temperature and concentration of gas for later development. After ovum puncture, the fertility is evaluated by viewing the ovums under a microscope. The ovums that have been fertilised, now considered as embryos, are cultivated within the proper medium to help them develop as embryos. On a selected day of cultivation (depending on each patient) the best embryos are selected to be transferred. The number of embryos to transfer is decided by each specific case with the couple's consent.

Transferring embryos is painless and does not require anaesthesia. The embryos are deposited in the uterus of the future mother through a silicone tube. The process can be followed with an ultrasound to determine the right location. It is important to highlight that the fact that the embryos are in the women does not mean that the women is already pregnant. In order for the embryos to become pregnant they must be implanted in the endometrium (the inner uterus tissue) and to know if she is pregnant we must wait 14 days from the aspiration of the ovocytes.

What probabilities are their of becoming pregnant?

As a whole, independently of the technique used, the percentage of pregnancy in our centre is around 45%. However, this percentage varies depending on many variables including the age, number of ovums obtained, the available embryos for transfer, the quality of embryo, etc.

FREEZING EMBRYOS


On occasion we obtain more embryos than is recommended to transfer. These embryos can be frozen and stored for future usage if gestation has not occurred in the IVF, or if pregnancy is not achieved and more children are desired. What is the transfer of frozen embryos? Transferring frozen embryos consists of thawing the embryos and then transferring to the uterus. There is neither need for puncturing to extract the ovums nor treatment for inducing ovulation; the transfer can be made during a natural cycle or an artificial cycle, which is much more comfortable for the patient, with less medication (basically just pills) and less check-ups. In both cases it is important to transfer the embryos on the proper day, when the uterus is prepared for implantation.
The rate of pregnancy after transferring frozen embryos is approximately 50% of the IVF.

How is the process performed in the lab?

The embryos are frozen with a programmable biological freezer and stored at extremely low temperatures (-196ºC) in liquid nitrogen, which allows us to conserve the physiological activity after thawing.
Upon thawing the embryos, some may not have survived the process, so to achieve optimal survival it is important to only freeze high quality embryos.


For some patients the embryos´ characteristics, patients or treatment evolution we suggest the use of specific lab techniques with the hope of improving results. These techniques include:

“ASSISTED HATCHING”
¿What is “assisted hatching?”

Hatching refers to the hatching of the embryo from its surrounding covering (film) to be implanted in the uterus. Assisted hatching is a lab procedure where a small rupture is made in the embryo's outer covering to enable its escape once transferred.

Who receives assisted hatching?

It is mainly indicated for patients 39 years or older. It can also help couples with gestation failure with In Vitro Fertilisation where there are not enough embryos to transfer the blastocysts.
TRANSFERRING BLASTOCYSTS:
PROLONGED CULTIVATION


What is prolonged cultivation?

This is the cultivation of embryos up to 5 to 6 days after fertilisation, where they then become blastocysts. Only some of the embryos cultivated develop into a blastocyst, but those that do have a higher possibility of being implanted and becoming impregnated.

Can the transfer of blastocysts always be performed?

An essential requisite for prolonged cultivation is an elevated number of high quality embryos to ensure obtaining at least one blastocyst. When we have a limited number of embryos, the cultivation of blastocysts is not advantageous.

 

 



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