In vitro fertilization (IVF)
In cases of obstruction of a woman’s fallopian tubes or in cases of severe male infertility, the recommended treatment is in vitro fertilization, followed by transfer of embryos into the woman’s uterus.
Ovum retrieval
Mature ova that have been released from the ovary are retrieved using a needle. A specialist physician uses ultrasound to guide the procedure. Retrieval is often combined with ovarian stimulation to better control ovulation.
With or without ovarian stimulation
Ovarian stimulation can follow the woman’s natural cycle, without the use of medication. In this case, the exact time of ovulation must be calculated. With this method, the physician can only retrieve a very small number of ova, and this must be done at the time of natural ovulation, which can happen at any moment.
Another method uses a combination of medications that allow the time of ovulation to be planned and stimulate the production of a greater number of mature ova. The woman takes one drug which interrupts the natural ovulation cycle, then at the appropriate time, takes another drug to bring on ovulation and cause several ova to mature.
In vitro maturation (actually not covered)
A new technique involves collecting ova that are still too immature to be fertilized. The ova are then incubated in vitro, i.e. outside the woman’s body. The advantage of this technique is that it does not require the woman to take medication to help the ova mature in her body. However, this is still considered a new procedure, and larger-scale studies are needed to demonstrate its safety.
Oocyte vitrification
Vitrification is a method for conserving ova that will not be used immediately following collection. This method is recommended for women who must undergo treatments, such as chemotherapy, that can cause premature ovarian failure (early menopause). The ova collected before treatment will be used when the woman is ready to have children.
Because human ova are very fragile and have a high water content, traditional freezing methods are unable to preserve the ova intact so they can be fertilized and begin a pregnancy after being thawed. Vitrification, or freeze-drying, increases the chances of success. This is a promising method, but its safety still needs to be proven.
Ovum donation
Women who do not produce any ova or ova of sufficient quality can receive donated ova. To avoid having to conserve the ova, the rest of the in vitro fertilization procedure is usually performed as soon as the ova are collected – unlike sperm donation, which can be done well in advance.
Embryo formation and preservation
Once the sperm and ova are collected, they are brought together in vitro. The sperm can then fertilize the ova to produce an embryo (called a zygote at this stage). The embryo is kept in conditions that promote cell division until it consists of six to eight cells. At that point, the embryo is cryogenically preserved at a temperature of ‑153 °C before being transferred into the woman’s uterus.
Intracytoplasmic sperm injection
When a man’s infertility is severe enough to prevent sperm from penetrating the wall of the ovum, fertilization can be assisted using intracytoplasmic sperm injection (ICSI). In this technique, a micropipette is used to inject a single spermatozoon selected by the embryologist through the wall of the ovum. Fertilization and cell division follow.
Go back to assisted procreation's page.
The information on this page was updated on August 6, 2010.
