In vitro fertilization (IVF), also known as test-tube babies, consists in promoting the encounter of the egg with the sperm outside the woman’s body. In normal conditions, this meeting occurs in one of the tubes. IVF changes the site of fertilization whenever this encounter does not take place as expected.
There are two kinds of in-vitro fertilization:
The eggs are mixed with the sperm in a nutrient “embryo culture” medium which simulates the tubes..
ICSI (intra-cytoplasmic sperm injection)
This consists in placing the sperm directly inside the egg. This method is adopted whenever we know it is not possible or chances are very slight that the sperm is able to fertilize the egg.
Even though it was initially idealized for the treatment of tubal problems, the use of IVF became more widespread in the treatment of other infertility factors:
- Blocked Fallopian Tubes (tubal disease) – When the tubes are blocked or damaged, a new site must be found for the meeting of the egg and sperm. It becomes necessary to remove the eggs from the ovaries before ovulation, so as not to lose them inside the woman’s body, and mix them together with the sperm in a medium outside the body similar to that of the tubes.
- All cases referred to IUI, but with no successful outcome – In some cases, after a couple undergoes a few unsuccessful attempts with simpler techniques such as insemination, ICSI is indicated since there may be some other reason interfering with pregnancy.
- Severe male factor – In some cases, the number and motility of sperm, as well as the amount of normal shaped sperm is so reduced that it becomes impossible to obtain an adequate number of type A sperm for fertilization to occur in the woman’s body.
- Severe endometriosis – Disorders in the physiology and anatomy of the female reproductive system may be so significant that it becomes completely impossible for the egg to meet the sperm inside the body, resulting in a healthy embryo.
The treatment using IVF / ICSI consists in stimulating the ovaries to produce more eggs in the ovulatory cycle of treatment. This cycle is completely controlled by the physician who will advise the patient on what medication to take. Preparing the ovaries for egg retrieval takes around 13 days and is monitored through ultrasound scanning 4 to 5 times during this phase. The scanning informs the physician the size of the follicles (structures inside the ovaries where the eggs grow) and the quality of the endometrium (inner layer of the uterus where the future embryo will be implanted and develop). The size of the follicles is related to the maturity of the eggs, which can only be fertilized by the sperm at a specific moment. Therefore, the ultra-sound scanning shows the physician the precise moment for egg retrieval.
Egg retrieval is done under (the patient sleeps during a short period of time) in an operating room close to the laboratory facilities where the eggs and sperm will be handled. The sperm is collected and processed on the same day so that they can be mixed with the eggs (conventional IVF) or injected in these (ICSI).
Fertilization results are analyzed sixteen to eighteen hours after mixing the eggs and sperm (the day following the egg/sperm gathering), and in most cases, fertilization occurs in approximately 80% of the mature eggs. On the third day after the retrieval, the patient undergoes embryo transfer and these are placed inside the uterus. When there are more good quality embryos than those necessary for the transfer, they may be frozen.