In Vitro Fertilization
In Vitro Fertilization
- assisted reproductive technology
In vitro fertilization, abbreviated as IVF, is a method used to enable couples who are unable to conceive naturally, to have a child. IVF refers to the combining of egg and sperm outside the woman's body. Once the egg is fertilized, the embryo is put back into the woman's body for full development.
Who is a candidate for the procedure?
IVF is used for women who have:
- blocked or absent fallopian tubes
- endometriosis, a condition in which tissue that normally lines the uterus is found elsewhere in the body
- other medical conditions that prevent the egg and sperm from joining naturally within the woman's body
How is the procedure performed?
Fertility medications (hormonal preparations) are used to help stimulate ovulation and to support the development of the uterine lining. These medications are taken daily, at home, usually by injection. Normally, the ovaries take turns releasing one egg each menstrual cycle. With IVF, fertility medications suppress normal hormone function and reduce the risk of eggs being released from the ovary before they can be retrieved.
Later in the cycle, different medications are given to cause the ovaries to produce many mature eggs at the same time. Vaginal ultrasound and blood testing every 2 to 3 days can monitor the body's response to these medications, and the maturity of the eggs. When enough eggs have matured, another type of medication is given to stimulate their release from the ovary. These mature eggs are removed 32 to 36 hours later.
The egg retrieval process is done in the doctor's office or special procedure room. The woman is sedated to keep her comfortable. An ultrasound device is inserted through the vagina to see the follicles in the ovaries that house the mature eggs. The doctor then inserts a needle through the vaginal wall and withdraws the eggs. This procedure takes 15 to 60 minutes, and usually only causes mild pelvic discomfort.
Once the eggs have been withdrawn, they are incubated for several hours before sperm cells are added. When the sperm cells are added to the eggs, they are again incubated for about 12 to 18 more hours to allow for fertilization. After fertilization occurs, the embryos are checked for quality and viability. Not all embryos will develop well enough to be transferred to the womb.
Embryos are usually transferred 3 to 5 days after egg retrieval. This transfer occurs in the doctor's office or procedure room. No anesthesia is used. It is much like a regular pelvic exam. The embryos are inserted into the uterus using a soft, flexible catheter attached to a syringe. Usually 2 to 5 embryos are inserted, depending on the quality of the embryos and the age of the woman. Extra embryos, if any, can be frozen for future use.
Those undergoing IVF need to consider what they will do with "excess embryos" once they have concluded their fertility treatments. Some patients are opposed to the destruction of embryos not transferred, or to their use in research. Donating the embryos to other infertile couples is an attractive option for some. However, some embryos do not survive the thawing process.
Embryos can remain frozen long-term (up to at least 13 years) and still remain viable. However, the storage is expensive, and the numbers of embryos in frozen storage nationwide continue to increase - over 400,000 by one conservative estimate in 2003.
Aronson D., National Infertility Association. Resolving infertility. New York, 1999