In Vitro Fertilization Phases Continued
The Fertilization Phase:
Fertilization will occur in a laboratory setting that mimics a woman's body. Sterile plastic plates (called Petri dishes), kept at body temperature, are filled with a substance (called a medium) that the eggs live in. Sperm is collected or thawed shortly before eggs are ready to receive it. While donor sperm is typically thawed from frozen storage, male partners produce a fresh sample via masturbation when this is possible. Collected sperm goes through a concentrating "wash" process which removes surrounding semen. Sperm and egg are then joined, either by directly injecting a single sperm into a single egg (e.g., ICSI), or by putting many sperm on the plate near an egg and allowing them to compete for entry as occurs under normal circumstances. Once a sperm has entered an egg, the merged cells are called an embryo. Embryos are typically grown on their petri medium for several days after fertilization so as to help weed out the weaker, less healthy embryos that have less of a chance at producing a viable pregnancy. The strong remaining embryos are then transferred back into your body or frozen.
The Transfer Phase:
Before embryos are placed back into your body, a special doctor, called an embryologist, will examine them to make sure they are good quality (i.e., appropriate number of cell divisions and structure). Once the quality is assessed, the embryos can then be transferred back into your body. The decision about how many embryos to place in your uterus must be made after discussions with a doctor and careful consideration of the risks and benefits. Transplanting a large number of eggs increases the likelihood of becoming pregnant. However, it also increases the likelihood of multiple gestations (more than one baby in the uterus). This is an important consideration because there is a higher risk of serious complications for each baby with multiple gestations. While the risks associated with a twin pregnancy are often considered acceptable, triplet pregnancies are generally considered dangerous. It is common to transfer 2 or 3 embryos; however, some couples transfer more. The number of embryos transplanted will depend on the number of previous IVF attempts, your age, and how many years you have has been infertile.
Once embryos are selected, they are placed in a catheter (a long tube). The catheter is then placed into your uterus through your cervix. The embryos are then deposited in the top of the uterus, where they would have been under non-assisted circumstances. This process is usually painless and only takes a few minutes.
The Implantation Phase:
To increase the likelihood that an embryo will implant in the uterus, you will take a hormone therapy (typically progesterone) starting the day after eggs are retrieved (Some women patients may also be asked to take progesterone therapy prior to egg retrieval so as to better manage the growth of the uterine lining where the egg will ultimately attach itself if a pregnancy occurs). Progesterone is a naturally occurring hormone, which thickens the lining of the uterus (called the endometrium) and makes it ready to nurture a growing baby. You will continue this medication for several weeks or months depending on your doctor's recommendation.
Once the embryos are transferred, they will either attach to the uterine lining or not, and a pregnancy will either occur or not. A blood or urine pregnancy test can be taken be taken to see if you are pregnant as soon as a week later. If the test is positive, an ultrasound will be used to make sure the pregnancy is in the uterus. An ultrasound will also be used to see a heart beat about six weeks after transfer. Once the heartbeat is detected, there is a 95% chance the pregnancy will continue on to a live birth.
If the pregnancy test is negative, progesterone therapy is stopped. You will go on to have your period and, afterwards can discuss further treatment options with your doctor. It is usually a good idea to wait at least a couple of months between cycles to allow your ovaries to rest before attempting assisted reproduction again.
IVF does not work every time, but it does tend to work more often than not. Further, the likelihood of in-vitro fertilization being successful is not significantly reduced until it has failed four times. If you undergo IVF one time and fail to become pregnant, this may simply reflect bad luck and not anything about you suggesting that you are a bad candidate for further IVF. If you have the necessary emotional and financial resources to continue you may choose to begin a new IVF cycle in the future. Allow yourself some time to grieve and be frustrated or angry about the negative outcome of the procedure if you need to. Then, prepare to draw on the same sources of support that you used for the first trial.