maturation are assessed by measuring the size of individual follicles with vaginal ultrasound and by measuring blood levels of estrogen.

When monitoring indicates that follicles have developed sufficiently, final maturation is initiated by injection of human chorionic gonadotropin and the retrieval of the eggs is scheduled approximately 36 hours later.

The egg retrieval procedure is performed under local anesthesia and although the patient is conscious, a combination of medications is used to facilitate patient comfort and relaxation. Mature follicles are identified by vaginal ultrasound and a needle is guided through the wall of the vagina and into each of the follicles. The follicular fluid containing the eggs is then aspirated into culture tubes for subsequent in vitro fertilization.

A semen sample is provided either shortly before or after the egg retrieval. The sample is assessed, appropriately processed and inseminated into defined media containing the eggs. Approximately 20 hours later, fertilization is assessed by identifying male and female pronuclei in the newly formed embryo. The fertilized eggs are cultured under strict conditions and examined carefully to assess their progress. On the third day of culture, the embryos are assessed and 2- 3 are selected for replacement into the uterus. The best quality embryos are chosen for replacement and remaining embryos are either frozen as day 3 embryos or cultured to the blastocyst stage (day 5) and then frozen. On the day of embryo transfer continuing embryo development is assessed by confirming that embryonic cells have divided.

The embryo transfer procedure is simple and requires no anesthesia. Between two and four embryos (usually 2-3) are transferred. The decision as to how many are transferred depends largely on the age of the woman and how many times she has undergone IVF in the past unsuccessfully. The embryos are loaded into a catheter, the catheter is passed through the cervix into the uterus and the embryos are deposited inside the uterus.

On the day of the embryo transfer, a woman will be asked to drink 2 or more glasses of water an hour before the procedure. This ensures the bladder is full. This is necessary to improve adequate visualization of the uterus at the time of embryo transfer. In the procedure room, a speculum will be inserted into the vagina and the cervix will be clean with fluid.

With an abdominal ultrasound as a guide, a fine catheter will be passed through the cervix and the embryo(s) injected gently into the uterus. Though it is not necessary to remain lying down after the embryos are replaced in the uterus, many women will choose to have a relaxing day.

There is a 12-day wait between the transfer and the expected date of the next period. During this time, it is important to continue taking progesterone supplementation and prenatal vitamins. After 12 days, a pregnancy test is done. During this time, the patient is encouraged to abstain from intercourse, restrict exercise to everyday activity only, and remain relaxed.

Risks
There are a number of risks associated with IVF.

Ovarian Hyperstimulation Syndrome (OHSS)
OHSS is a condition that can arise with the use of the medications used to stimulate the ovaries (FSH). The exact cause of OHSS is not known but it is thought to arise from the stimulate of a hormone called VEGF that then leads to leaky vessels in the body. This can lead to accumulation of fluid around the ovaries and other organs in the abdomen, even fluid in the lungs. This can happen in up to 10% of IVF cases but is only severe leading to hospitalization in less than 1%. Hospitalization is often recommended because of severe abdominal discomfort, decreased urine output and excessive thickening of the blood that may lead to blood clots. OHSS is characterized by enlargement of the ovaries, fluid retention and weight gain. Symptoms of OHSS include feeling bloated, abdominal discomfort, nausea, vomiting, and in extreme cases – difficulty breathing.

If the risk of OHSS is high, some of the following may be recommended:

• Record weight daily
• Measure abdominal girth at the umbilicus (i.e. belly button level)
• Encourage fluid intake. Fluids should include water and electrolyte-containing fluids (Gatorade).
• Monitor your urine output.

In some cases, it might be necessary to drain some fluid from the abdomen. This can be done by passing a fine needle through the vagina or through the abdominal wall to drain the fluid.

Although extremely uncommon, OHSS can be life threatening. However, the condition is self limiting. It usually resolves on its own, or by doing what is prescribed above. However, it can persist longer (up to 3 weeks) in women who are pregnant.

Multiples
As the success of IVF has increased over the years, the risk of multiples has increased also. Because of this most physicians will limit the number of embryos being replaced to no more than 3 in women over the age of 36 and 1-2 in women less than this age. Obviously, by limiting the number of embryos replaced, it is possible to limit the risk of triplets and beyond. Even twins can carry significant risks. These include premature delivery, developmental abnormalities and underweight babies. Maternal risks of twins and triplet pregnancies include hypertension of pregnancy and gestational diabetes. So although in most cases the outcome with twins is good, there are significantly increased risks over singleton pregnancies. Triplets and quadruplets can even greater risks of pregnancy. If a pregnancy with triplets or more does occur, some couples may consider selective reduction to avoid these extremely high risks.

Other risks:
As with other surgical procedures, bleeding, infection and allergic reactions to medications are occasionally encountered.

Pregnancy Outcome Risks
Prematurity with IVF a risk, even when not multiples?
yes, appears so.