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.
Step 1: 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.
Step 2: 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.
Step 3: Sperm, usually obtained by ejaculation is prepared for combining with the eggs.
Step 4: 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.
Step 5: 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.
How successful is in vitro fertilization?
The success rate of IVF clinics depends on a number of factors including patient characteristics and treatment approaches. It is also important to understand that pregnancy rates are not the same as live birth rates. In the United States, the live birth rate for each IVF cycle started is approximately:
- 30 to 35% for women under age 35
- 25% for women ages 35 to 37
- 15 to 20% for women ages 38 to 40
- 6 to 10% for women ages over 40
The success rates of individual clinics are published on the web site of the Centers for Disease Control and Prevention.
When comparing success rates of different clinics, it is important to know what type of pregnancies are being compared. A chemical pregnancy is one confirmed by blood or urine tests, but in a clinical pregnancy where pregnancies are typically verfied through ultrasound, a miscarriage may occur before the pregnancy can be confirmed. After a clinical pregnancy has been verified, a miscarriage may still occur, but it is less likely.
What if I don’t produce healthy eggs or my husband is sterile?
IVF may be done with a couple’s own eggs and sperm or with donor eggs, sperm, or embryos. Some couples choose to use donor eggs, sperm, or embryos because of genetic concerns. Donor eggs are used in approximately 10% of all assisted reproductive technology (ART) cycles.
What are the risks associated with in vitro fertilization?
As with most medical procedures, there are potential risks. The risks of in vitro fertilization correspond with each specific step of the procedure.
Ovary stimulation carries the risk of hyperstimulation, where the ovaries become swollen and painful. This condition, "Ovarian Hyper stimulation Syndrome", is usually rare, mild, and involves the following potential side affects: nausea, vomiting, lack of appetite, or a feeling of being bloated. More severe symptoms that occur in 1% of cases, include the following:
- Severe abdominal pain
- Severe nausea or vomiting
- Decreased urinary frequency
- Dark-colored urine
- Shortness of breath
- Ten pound weight gain within three to five days
Egg retrieval and the use of laparoscopy carry the typical risks associated with receiving anesthesia. Additionally, there is a slight risk of bleeding, infection, and damage to the bowel, bladder, or blood vessel. Less than one patient in 1,000 will require surgery to repair damage caused during the egg retrieval process.
The chance of a multiples pregnancy is increased in all assisted reproductive procedures. There are additional risks and concerns related to multiples during pregnancy including the increased risk of premature delivery.
Assisted reproductive technology (ART) involves a significant physical, financial, and emotional commitment on the part of a couple. Psychological stress and emotional problems are common, especially if IVF is unsuccessful.
How many embryos should be created or transferred?
The number of embryos that should be created or transferred during any single IVF cycle is subject to debate. Some medical literature states that transferring no more than four embryos per IVF cycle will yield optimal results. Transferring more than four is believed to result in excess numbers of multiple pregnancies, increasing the possibility of additional complications.
Transferring four embryos instead of only one or two increases the probability that pregnancy will occur. However, it is important to realize that all four embryos could implant. Some individuals have serious concerns regarding what happens to leftover embryos. In any case, these are matters that couples should thoroughly discuss with their physician.
How do I choose an infertility clinic?
There are a number of questions to ask regarding the cost and details of specific centers and fertility programs. Some suggested questions are available online in Selecting Your ART Program.
