What to Expect During an Egg Retrieval and Embryo Transfer
Often times the IVF cycle is preceded by a 3-week course of oral contraceptives. Some literature has suggested that success rates are better following a 3-week course of ovarian suppression. The stimulation always begins at the start of the cycle in which the eggs will be retrieved and usually is between the second and fourth days of the cycle.
Typically a patient undergoing fertility treatment will be given instructions for injections for 4 days and then instructed to return to assess the response which we determine with an ultrasound to measure the size of the growing follicles, the small cysts which contain the eggs, and the blood estrogen level which is the primary byproduct of the developing cycles. Once we determine that the eggs are mature with the ultrasound measurements and estrogen levels, we use a different hormone to trigger ovulation.
The egg retrieval has to be precisely timed so that we can retrieve the eggs shortly before the ovaries would otherwise release them. Once they are released into the pelvis it becomes much more difficult to recover the eggs and the usual time interval from the injection to the planned time of the retrieval is approximately 34 hours, but we do allow a few hours grace period. The egg retrieval is done with IV sedation so you should be very comfortable through the procedure. You may experience some pelvic discomfort for a day or so after the procedure. Since it is surgery there are potential complications and these include bleeding, infection, damage to other organs, and problems with the anesthesia. In practice, all of these complications are extremely rare.
The eggs are removed using a vaginal ultrasound with a needle guide so that the ovary can be entered through the back wall of the vagina where it is very thin and the fluid within the follicles containing the eggs is then drawn through the needle, collected in a test tube, and given to the laboratory for identification of the eggs. On the same day of the retrieval, the eggs will be fertilized either by adding a predetermined concentration of sperm to the dish containing the egg or by injecting a single sperm directly into the egg, ICSI (intracytoplasmic sperm injection).
The following day we will be able to determine whether the eggs fertilized or not and they are then observed for 3 to 5 days after the egg retrieval. Depending on how they are developing they may be transferred either 3 or 5 days after the retrieval. The recommendations number of embryos to be transferred depends on the patient's age and for most women under the age of 35 we are recommending 1, no more than 2 embryos be transferred. For women over the age of 39 we will transfer up to 5 embryos. This reflects the higher proportion of abnormal embryos in older women and even though more embryos are transferred, the pregnancy rates and multiple pregnancy rates are lower in older women. The most common reason an IVF cycle is unsuccessful is because the embryos produced have the wrong number of chromosomes to develop into a normal embryo.