The first step for an In Vitro Fertilization program is stimulation of the ovaries with medication. This is necessary for the development of many follicles and lasts about 12-14 days. The stimulation protocol is chosen based on each couple’s medical history (age, previous attempts, etc). Monitoring is done every 2-3 days with hormone determination & ultrasound examination for the appropriate dose of drugs. When most of the follicles reach 18-20 mm in diameter, the last injection is given, which will result in the final maturation of the oocytes and ovulation.
The day and time of oocyte pick up is programmed when the follicles reach the appropriate size (18-20mm). Oocyte collection is performed intervaginally with mild sedation and ultrasound monitoring. The method is short in duration and painless. On the same day, the husband’s semen is collected in a specially designed room (men’s room) for this purpose. The sample is prepared with appropriate culture media in order to be ready to be used for fertilisation. In cases of azoospermia testicular biopsy (TESE) or sperm donor selection is proposed.
After oocyte collection, the next step is fertilization. This represents the main laboratory stage of your attempt. There are two fertilisation methods available:
In case of IVF, the appropriate number of spermatozoa is placed in culture medium that contains the oocytes. There is no further intervention. The spermatozoa approach the egg on their own and one of them penetrates it and fertilises it. In ICSI cases, the embryologists using highly specialised equipment choose one good morphologically spermatozoon from the sample and deposit it inside the oocyte to induce activation and fertilisation. Only one motile spermatozoon is required for each egg. Each injection usually lasts for a few seconds, but the entire procedure may take several hours to complete, especially in cases of high oocyte numbers or extremely low sperm numbers. The method has been successfully used since 1992 and overcomes almost all the barriers that cause male infertility.
On the first day after oocyte collection, fertilisation checking occurs. The embryologists check the oocytes for the appearance or not of the two pronuclei, one of maternal and one of paternal origin. At this stage cell divisions have not yet begun. Embryos remain in the incubator for the next few days until embryo transfer and are evaluated by embryologists on the 3rd and / or 5th day of their culture according to international criteria. From the first day up to the 3rd day when cleavage occurs, the embryos are between about 2-10 cells depending on the culture day. After the 3rd-day blastomere compaction begins to form the morula (day 4) and then the blastocyst (day 5 to 6).
Shortly before the embryotransfer a small opening or thinning is created in the zona pellucida of the embryo using a special laser. The process is repeated for each embryo and is called assisted hatching. The technique of assisted hatching is recommended in cases where the zona pellucida of the embryo is believed to be thick and stiff to prevent implantation. This helps the release of the embryo from the zona pellucida and its implantation.
The number of embryos to be transferred is decided by the treating physician and the embryologist, taking into account the age of the woman, embryo quality and her medical history. The embryos are selected for embryo transfer based on international criteria and their embryo transfer can take place between the 2nd and the 6th day of their culture. Embryo transfer is performed via a special catheter. The embryologist takes the selected embryos into the catheter in a minimum volume of culture medium. The gynaecologist inserts the catheter into the uterine cavity where he places the embryos under abdominal ultrasound guidance. After embryo transfer, the embryologist checks the catheter that all embryos were transferred.