In Vitro Fertilization

A couple experiencing infertility problems can seek help through a number of assisted reproductive techniques. One of the most common is in vitro fertilization (IVF), which combines a man's sperm with a woman's egg outside of the body then transfers one or more fertilized eggs into the woman's uterus for implantation, hopefully resulting in pregnancy.

IVF can be performed with a couple's own sperm and eggs. However, if there is a problem with either the man's sperm or the woman's eggs, a couple can also use donor sperm and/or eggs, or in some cases, donor embryos, which do not share any genetic material of the prospective parents.

When a couple begins IVF therapy, if the plan is to use the woman's eggs, she is often given a course of oral contraceptives (birth control pills), to regulate her monthly cycle in preparation for the IVF treatment. Around the time the woman is due to begin her menstrual period, an ultrasound examination is performed, to examine her ovaries to make sure there are no impediments to egg development. Blood tests will also be taken during this time, and if these baseline levels are acceptable to the clinician, IVF treatment will begin.

These are the basic steps in an IVF treatment cycle:

Ovarian Stimulation

During the ovarian stimulation phase (also know as ovulation induction), a woman takes medication, commonly known as fertility drugs, to cause multiple eggs to grow in her ovaries. Normally, only one egg (the medical term is oocyte) develops inside a woman during each monthly cycle, but multiple eggs are desired during IVF treatment because some usually don't become fertilized or develop normally after fertilization.

Fertility drugs are taken for about a week to ten days and are administered both orally and by injection. Ultrasound examinations monitor the growth and development of ovarian follicles, fluid-filled sacs where the eggs are contained. Using ultrasound and blood tests to measure hormone levels, the doctor is able to determine if medication levels have to be adjusted for proper follicle development and decide when it's time to attempt egg retrieval. When the follicles appear ready, additional medication is given to ensure the final stage of egg maturation, so that the eggs will be at optimal readiness for fertilization after retrieval. This is a carefully-timed procedure: if the medication is given too early, the eggs won't be mature enough; if too late, the eggs may be too old for fertilization to take place.

Egg Retrieval

Eggs are retrieved directly from the ovaries before ovulation occurs, about 34-36 hours after the final medication is given. The retrieval process is a minor, outpatient surgical procedure called follicular aspiration (or transvaginal ultrasound aspiration). During egg retrieval, an ultrasound probe is inserted into the vagina, and a hollow needle is then guided through the vagina up into the ovaries. The needle suctions out all mature follicles from both ovaries, and the follicles are then placed in an incubator. The retrieval process usually takes between 15-30 minutes, and on average about 5-15 follicles are retrieved. Anesthesia is administered so that the woman will not feel any pain; there may be some spotting and cramping following egg retrieval, but this is temporary. At around the same time as retrieval, the woman begins taking progesterone supplements. Progesterone is a female hormone that prepares the uterine wall for implantation of a fertilized egg.

Fertilization and Embryo Culture

Once the eggs have been retrieved, they are examined for maturity and quality. Viable eggs are placed in a special fluid called IVF culture medium until fertilization, which takes places within 12-24 hours of aspiration. A semen sample collected the same day as egg retrieval or earlier (and frozen) is "washed," a laboratory procedure that separates sperm, the male reproductive cells, from other seminal fluids. Thousands of viable, motile (well-moving) sperm are then placed in a culture dish with just one oocyte. The culture dishes are incubated overnight in a carefully controlled environment and then examined to see if fertilization has taken place. Alternately, in the case of poor semen quality or other challenging factors, an individual sperm can be directly injected into each mature egg; this process is called intracytoplasmic sperm injection (ICSI). Once fertilization occurs, the fertilized egg divides into an embryo, and growth is monitored for several days before the embryo is transferred to the woman's uterus.

Embryo Transfer

Embryo transfer can take place at any time between 1-6 days after egg retrieval. A catheter (a thin tube) is passed through the cervix into the uterus, and one or more embryos are deposited into the uterine cavity. The number of embryos transferred generally depends on the age of the woman. After the transfer, the woman remains in a supine position (lying down) for a few hours.  Sometimes there are embryos remaining that were not transferred during an IVF procedure; these can be frozen and cryo-preserved for later use if future IVF cycles are needed.

After embryo transfer, it takes about two weeks for a woman to find out whether or not she is pregnant. If she is, the pregnancy will be closely monitored in its early weeks for signs of miscarriage or ectopic pregnancies. The IVF doctor will also determine if the IVF has resulted in a multiple pregnancy. Multiple pregnancies are a common result of IVF procedures when more than one fertilized egg is transferred. If the pregnancy is proceeding smoothly after about two months, the woman's care will then be taken over by an obstetrician. If, however, the IVF treatment has not worked and the woman is not pregnant, the couple must decide whether or not to try again.