How IVF Works
In vitro fertilization (IVF) and embryo transfer has six basic steps, taking one to two months for the entire treatment cycle.
Normally, the ovaries stimulate a single egg to develop each month. Fertility medications used in IVF are prescribed to increase the number of eggs that develop so more can be collected during a cycle. This is called superovulation induction or controlled ovarian hyperstimulation. For a successful IVF cycle, multiple eggs are desirable because some will not fertilize correctly and others may not develop into embryos. Ultrasound allows the ovaries to be monitored for egg development to help time the IVF procedure. A doctor will also use blood samples to check estrogen hormone levels.
The woman’s eggs are retrieved using a transvaginal ultrasound aspiration, a minor surgical procedure. Ultrasound imaging guides a hollow needle into the ovary to collect the eggs. Multiple eggs can be removed in less than half an hour. Sedation helps the patient to not feel discomfort during retrieval. After the retrieval, the woman may experience cramping, but this subsides by the next day. The ovaries become enlarged during the procedure, which can last for several weeks, so the woman may feel pressure or fullness.
Sperm is obtained by ejaculation or in a special collection condom during intercourse, or may be collected directly from the testicle or vas deferens if there is an obstruction or lack of sperm production. The man providing the sperm sample is usually advised to abstain from ejaculating for two to three days prior in order to increase sperm count and pregnancy chances. Once collected, the sperm are separated from the semen and washed before they are combined with the egg.
Insemination, fertilization, and embryo culture
For the IVF insemination process, the sperm and eggs are put together for fertilization in an incubator overnight. If the man has poor sperm quality, intracytoplasmic sperm injection (ICSI) may be performed to inject a single sperm directly into an egg. The eggs are checked the day after for growth. Approximately 50 percent to 70 percent of mature eggs will be fertilized in the incubator or using ICSI.
Embryos are transferred into the uterine cavity on the second, third or fifth day after the retrieval. A speculum is inserted into the vagina, exposing the cervix, and a predetermined number of embryos suspended in media are transferred through a catheter into the womb. This process is usually guided by ultrasound. Some women may experience mild cramping, but transfer is usually painless.
After the embryo(s) are successfully inserted into the uterus, the woman is discharged so she can go home. While bed rest is often encouraged, there is no evidence that this has any beneficial effects to increase pregnancy rates. A blood test and possibly an ultrasound will determine if the implantation was successful, and pregnancy has occurred.