Procedure of IVF
Monitoring of the follicular growth
Women are born with a finitive number of oocytes, approximately 1 million at birth. This number is gradually reduced, reaching approximately 450,000 at the age when menstruation begins.
Every month the number of premature oocytes that enter the maturation phase is about 1,000 but only one ot two are growing and finally ovulating. The rest remain unruptured and destroyed.
There are two ways to collect the oocytes freom the ovaries during in vitro fertilization (IVF).
At first, after hormonal stimulation of the ovaries with some drugs called gonadotropins.
Second, during a natural cycle.
What is hormonal stimulation of the ovaries?
The aim of the hormonal stimulation of the ovaries is the maturation of more than one or two oocytes.
For this purpose, it is necessary to administer hormones (FSH and LH) that called gonadotropins.
These hormones are mimicking the natural hormones that are secreted from the pituitary gland during the normal menstrual cycle.
These hormones are administered subcutaneously or intramuscularly.
What is the main factor that affects the number of oocytes?
The age of the woman! The older the women the lesser the number of the oocytes, i.e. when we give the same dose of gonadotropins (FSH/LH) to a young and an older woman, young women will make significantly more oocytes!
Shall I enter menopause earlier if I get drugs?
Of course not! The oocytes that grow during ovarian stimulation for in vitro fertilization were those that were otherwise destroyed during a natural procedure of the cycle that called atresia. During every cycle, there is a pool from 10-15 oocytes that can be used. During natural cycle one is selected and ovulates and the rest are destroyed. By giving drugs we “rescue” these 10-15 oocytes from being destroyed!
How do we do the monitoring of the follicular growth for in vitro fertilization?
With frequent ultrasound scans of the ovaries to see how follicles are growing combined with hormonal measurements (mainly E2-estradiol). This lasts about 10-12 days.
When we have a number of follicles (preferably more than three) over 18mm we inject a hormone that is called HCG that matures the oocyte and 36hours later we collect it.
Do we have other protocols for in vitro fertilization?
For low responders i.e women that cannot produce enough oocytes with gonadotripins we may do in vitro fertilization in a natural cycle.
There are also some other protocols like combined natural cycle with gonadotropins. Some other women may benefit from Clomiphene citrate.
What are the complications of ovarian stimulation?
In less than <1% of women ovarian hyperstimulation syndrome may occur.
Are there any preventive measures for OHSS?
a) administration of smaller doses of hormones during ovarian stimulation
b) “coasting” i.e. interruption of hormonal stimulation for some days prior to oocyte collection, in order to reduce oestradiol levels
c) collect, fertilize oocytes but freeze all the embryos and transfer them in a subsequent cycle)
d) give cabergoline
d) in serious conditions, completely interrupt treatment and “cancel” the stimulation cycle.
