the IVF process

In vitro fertilization (IVF) is what comes to mind for most people when they think about infertility treatment. This is not surprising given the increasing use of IVF over the last 10 years.

The basic premise of all assisted reproductive technology (ART) is that the fertilization process (union of the sperm and egg) and embryo transfer process (placement of the embryo into the uterus) is aided by a fertility clinic laboratory. The IVF technique was initially designed for treatment of women with tubal infertility since the fallopian tubes are bypassed entirely with IVF. Eggs are retrieved from the body and inseminated in a lab with semen from a partner or a donor. The resulting embryos are transferred to the uterus in a separate procedure.

• egg retrieval
• fertilization
• embryo transfer

egg retrieval

Drugs that help induce the release of mature eggs from the ovary like clomiphene or gonadotropins are used to stimulate the ovaries for IVF. The most common stimulation protocol uses gonadotropins with GnRH analogues, either GnRH antagonists or GnRH agonists.

You should discuss all medications with your healthcare provider and have a clear understanding of when you start and stop each medication.

Egg retrieval is performed about 36 hours after human chorionic gonadotropin (HCG) is given to mature the eggs. Light anesthesia is administered, and the eggs are usually removed by ultrasound guided retrieval or, less commonly, by laparoscopy. The follicles and the eggs and fluid which surround them are aspirated into a tube that is then given to the embryology lab (see below).

The procedure itself has minimal risks but post-operative cramping is common. Intra-abdominal bleeding and infection are two possible side effects however these are quite rare. Recovery time is generally short – one to one and a half hours.

top

fertilization

The embryologist looks for eggs in fluid aspirated from the follicles. The eggs are assessed for maturity and incubated. The male partner is asked to collect a semen sample if fresh sperm is used. A semen analysis is performed and the sample is washed with a special solution of nutrients to isolate the more motile sperm. Fertilization is done in the lab. The exact process used depends on the type of infertility problem and clinic preferences. In standard IVF, the sperm is placed into the dish containing the egg. Some fertility clinics perform intracytoplasmic sperm injection (ICSI) routinely for reasons other than male infertility.

ICSI is a remarkable technique that has revolutionized infertility treatment for severe male factor infertility. One sperm is drawn up in a needle and then injected into the egg. The actual injection process takes less than 60 seconds.

• Less than one minute after the needle is withdrawn, the egg will return to its original shape.
• Within 18 hours, the embryologist can determine if fertilization has occurred.
• In 24 to 72 hours, the embryologist can determine if the embryo is growing.

The sperm and eggs (oocytes) are placed in growth media containing special nutrients that allow them to live outside the body. The egg when fertilized by sperm becomes an embryo that is allowed to grow and divide in the laboratory for two to five days in the special culture media.

top

embryo transfer

Transfer usually occurs two to five days after fertilization depending on the number and quality of the embryos and the clinic policy. Healthcare providers will often transfer more than one embryo into the woman's uterus to increase the chances of pregnancy. However, the number transferred depends on the age of the woman, the quality of the embryos, and the success rates of the clinic. The current trend is to transfer one to two good embryos to reduce the risk of high order multiple pregnancy (triplets or more).

The embryo culture systems currently used allow the embryos to develop to the blastocyst stage (days 5-7) instead of days 2 to 3. The extra days in culture assist the embryologist in selecting better embryos for transfer. This means that fewer embryos (one to two usually) are transferred without compromising pregnancy rates. It also means that the risk of multiple pregnancy is reduced. The process of natural selection determines which embryos grow to the blastocyst stage since some will arrest before then. On average 40% to 50% of the fertilized embryos will continue developing into blastocysts.

top