In Vitro Fertilization
is commonly referred to as IVF. IVF is the process of fertilization by manually combining an egg and sperm in a laboratory dish. When the IVF procedure is successful, the process is combined with a procedure known as embryo transfer, which involves physically placing the embryo in the uterus.
What is involved with In Vitro Fertilization?
There are five basic steps in the IVF and embryo transfer process which include the following:
Monitor and stimulate the development of healthy egg(s) in the ovaries.
Collect the eggs.
Secure the sperm.
Combine the eggs and sperm together in the laboratory and provide the appropriate environment for fertilization and early embryo growth.
Transfer embryos into the uterus.
Fertility medications are prescribed to control the timing of the egg ripening and to increase the chance of collecting multiple eggs during one of the woman’s cycles. This is often referred to as ovulation induction. Multiple eggs are desired because some eggs will not develop or fertilize after retrieval. Egg development is monitored using ultrasound to examine the ovaries, and urine or blood test samples are taken to check hormone levels.
Eggs are retrieved through a minor surgical procedure that uses ultrasound imaging to guide a hollow needle through the pelvic cavity. Sedation and local anesthesia are provided to reduce and remove potential discomfort. The eggs are removed from the ovaries using a hollow needle, a procedure called follicular aspiration. Some women may experience cramping on the day of retrieval, which usually subsides the following day; however, a feeling of fullness or pressure may continue for several weeks following the procedure.
Sperm, usually obtained by ejaculation is prepared for combining with the eggs.
In a process called insemination, the sperm and eggs are placed in incubators located in the laboratory. The incubators enable fertilization to occur. In some cases where there is a lower probability of fertilization, intracytoplasmic sperm injection(ICSI) may be used. Through this procedure, a single sperm is injected directly into the egg in an attempt to achieve fertilization. The eggs are monitored to confirm that fertilization and cell division are taking place. Once this occurs, the fertilized eggs are considered embryos.
The embryos are usually transferred into the woman’s uterus from one to six days later, but in most cases the transfer occurs between two to three days following egg retrieval. At this stage, the fertilized egg has developed into a two-to-four cell embryo. The transfer process involves a speculum which is inserted into the vagina to expose the cervix. A predetermined number of embryos are suspended in fluid and gently placed through a catheter into the womb. This process is often guided by ultrasound. The procedure is usually painless, but some women experience mild cramping.
These steps are followed by rest and watching for early pregnancy symptoms. A blood test and potentially an ultrasound will be used to determine if successful implantation and pregnancy have occurred.
Are there variations of in vitro fertilization?
Gamete intrafallopian transfer (GIFT) and zygote intrafallopian transfer (ZIFT) are two procedures related to IVF.
GIFT is similar to IVF, but the gametes (egg and sperm) are transferred to the fallopian tubes rather than the uterus, and fertilization takes place in the tubes rather than in the laboratory. GIFT also involves a laparoscopic surgical procedure to transfer the sperm and egg into the tubes. GIFT accounts for approximately 2% of assisted reproductive technology (ART) procedures in the United States.
ZIFT differs from GIFT in that the fertilization process still takes place in the laboratory versus the fallopian tubes. It is similar to GIFT in that the fertilized egg is transferred into fallopian tubes, and it involves a laparoscopic surgical procedure. ZIFT accounts for less than 1.5% of assisted reproductive technology (ART) procedures in the United States.