With IVF, which is the most well-known method of medically assisted reproduction, embryos can emerge from the genetic material of two mates but also from donor eggs or sperm. Also, eggs can be used immediately after egg collection but also cryopreserved eggs, sperm or embryos.
In vitro fertilization is divided into four main stages. A basic condition for starting the procedures is the detailed examination of the couple’s history and the counseling for the selection of the appropriate personalized approach.
Ovarian stimulation: It is performed for the production and maturation of multiple follicles.
Physical cycle
In many cases IVF is recommended in a natural cycle, without causing ovulation. In the natural cycle the ovary produces and matures a usually follicle. With regular ultrasounds and hormonal control, the progress of the development of the single follicle as well as the endometrium is monitored, without the administration of drugs for the stimulation of the ovaries. Once the follicle has reached the appropriate size and hormone levels (estradiol and luteinizing hormone) are determined, a single dose of hormone is given to help the egg mature.
Modified natural cycle
From the 2nd to the 6th day of the cycle, treatment is taken with clomiphene citrate or letrozole tablets in order to produce more than one egg.
Controlled ovarian stimulation
In order to increase the chances of IVF success they need more than one egg. For this reason, injectable drugs are given to help the follicles mature (causing ovulation). At regular visits, hormones are measured and the thickness of the endometrium is estimated, as well as the number and diameter of the follicles that develop in the ovaries. Ovarian stimulation lasts about 9 to 12 days.
Egg collection
After the end of the stimulation and at the discretion of the treating physician, a chorionic gonadotropin injection follows, which helps the follicles to mature. After 36 to 38 hours, ovulation follows. The procedure is performed under the influence of light anesthesia (intoxication).
Fertilization
The eggs obtained are fertilized in the laboratory. The next day of ovulation we know the number of eggs that were fertilized and the exact day and time of embryo transfer is determined. The procedure to be followed is determined by the type and quality of the sperm
If after the preparation of the sperm its parameters (concentration, morphology, motility) are at normal levels, a few hours after ovulation the embryologist places the eggs and a certain number of activated sperms in a special nutrient culture medium. The sperm, without any other intervention, come in contact with the egg and one of them penetrates inside it and fertilizes it, as a result of which the creation and development of the fetus begins.
The fertilization test is done 16-20 hours later. If fertility problems are identified that are related to sperm quality such as low sperm content / motility, low sperm quality or azoospermia, the method of Microfertilization (ICSI, IntraCytoplasmic Sperm Injection) is the solution. In ICSI, the sperm is injected into the egg through a very fine needle.
Embryo transfer
It is the last stage. It can take place 2-6 days after ovulation. The number of embryos transferred is decided by the doctor and the embryologists after discussion with the couple and based on the legislation.
This is a simple and painless procedure, which is performed using special catheters and under ultrasound guidance. The woman for the next 4 days is advised to refrain from any intense physical activity. 10-14 days after embryo transfer, a β-chorionic gonadotropin measurement is performed to diagnose pregnancy. If good quality embryos have emerged that have not been transferred to the uterus, they can be frozen and reused in a possible next IVF cycle.
Writes:
Vassilios D. Kellaris
Obstetrician – Reproductive Gynecologist
Scientific Associate of the HYGEIA IVF Embryogenesis Unit
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