In these cases, the union of eggs and sperm (conception) is performed in the embryology lab, and the fertilized
egg(s) are incubated. Once the embryos are developed, one of them is selected to be placed (transferred) into the
uterus.
These techniques include: In vitro fertilization eggs with embryo transfer (IVF/ET) and intracytoplasmic sperm injection
with embryo transfer (ICSI/ET); especially indicated for couples with long-standing infertility, for severe causes of
infertility or for those who have unsuccessfully tried other treatments previously. The use of IVF or ICSI depends on
the quality of the couple's semen sample.
Conventional IVF is indicated for normal or slightly altered semen samples. In this technique, a certain number of
sperm is placed around each egg, and fertilization is awaited.
ICSI is used when the semen sample shows a low quantity or quality of sperm (called severe male factor), and a
single sperm is injected into the egg using a microscope with a micromanipulator.
Both procedures are performed in a highly complex embryology laboratory, under strictly
controlled environmental conditions of temperature, pH, humidity, oxygen concentration and carbon dioxide concentration, with special culture media in incubators especially designed for human embryo development. If fertilization occurs with either technique, the so-called pre-implantation embryos or pre-embryos are developed.
PROCEDURES FOR BOTH TECHNIQUES ARE EQUIVALENT.
During a natural ovarian cycle, only one egg has the opportunity to be fertilized. The goal of ovarian stimulation is to recruit a large number of eggs from both ovaries for in vitro fertilization. Ovarian stimulation is achieved by hormonal administration during 10 days on average. It may produce some discomfort, especially swelling in the pelvis, mood swings and breast tenderness.
During the stimulation period, serial transvaginal ultrasounds are performed to evaluate follicle growth and development, and some blood samples may be necessary in order to measure hormone levels.
Once most of the follicles have reached an average size of more than 17 mm, a hormone called hCG (chorionic gonadotropin) is injected to complete the maturation of the eggs, and 35 to 36 hours later follicular aspiration is scheduled.
Follicular aspiration involves retrieval of the eggs from each follicle by puncturing the ovaries. It is an outpatient procedure performed under intravenous sedation, and it usually lasts for 20 to 30 minutes. After the procedure, the patient will rest in a recovery room for a short period before being discharged to complete recovery for the rest of the day.
On the day of the follicular aspiration, a semen sample will be needed. It is obtained by masturbation as long as there are sperm in the ejaculate (even if there is reduced amount). The sample can be produced at home if you are less than one hour away, or it can be obtained in OVUM’s semen sampling room. The semen is processed in the laboratory and placed in culture media to select the most suitable spermatozoids.
In case of the absence of spermatozoids (azoospermia), they can be obtained via a testicular biopsy. This requires a small surgical intervention and is usually performed some days in advance and the sperm obtained is kept frozen until it is used.
The patient should begin daily hormone supplementation with progesterone on the night of the follicular aspiration. The most common route of administration is intravaginal.
Immediately after retrieval, eggs are classified according to their appearance and degree of maturation and left in an incubator for about 3 hours before fertilization by IVF or ICSI. Fertilization can be confirmed one day after egg retrieval. If the eggs and sperm are normal, the average fertilization rate is about 70%. This rate varies according to the morphological characteristics of the eggs and sperms, woman's age, quality of the semen and the cause of infertility. Unfortunately, in some patients with only few eggs retrieved and/or with a very low oocyte quality fertilization may not be achieved.
A high percentage of the eggs have genetic anomalies that can either prevent fertilization, cause the embryo to stop developing, or give rise to pre-embryos that will not implant. The chances of producing eggs with chromosomal abnormalities increase with women’s age, being around 35-40% in women of 35 years old, and greater than 70% in women over 40 years old.
About 25 hours after the insemination of the eggs with the sperm, two cells can be seen in normal embryos, and during the following days, the development of these pre-implantation embryos or pre-embryos will be monitored in the lab. Normally, at 48 hours, 2-4 cells are seen, at 72 hours 6-12 cells, and on the 5th or 6th day, the blastocyst stage (80-130 cells) will be reached. Depending on medical criteria (embryo quality, patient's age, number of embryos available), embryo transfer into the uterine cavity can be performed at any pre-embryo stage.
Embryo transfer into the uterus is performed in a designated room adjacent to the embryology lab. The procedure takes about 10 minutes and consists of depositing the embryos into the uterine cavity using a thin plastic catheter (transfer cannula) under ultrasonographic guidance. In most cases, this is a straightforward procedure with no need for analgesia or anesthesia.
Following embryo transfer, relative rest is recommended for 24 hours. Several studies have shown that prolonged bed rest does not improve pregnancy rates.
About 9 to 13 days after embryo-transfer, specific hormonal levels (ßHCG) can be measured in the woman's blood to document the presence of pregnancy. Once pregnancy is confirmed, the test is repeated on the following days to check for appropriate rising of hormonal levels. About 21 days after the embryo transfer, a gestational sac can be visualized inside the uterus by transvaginal ultrasound, and only 28 days after the transfer cardiac activity is seen in the embryo.
The success rate of assisted reproduction procedures is mainly determined by:
- The age of the woman.
- The number and maturity of the eggs obtained.
- The quality of the semen used.
- The quality of the embryos transferred.
- The condition of the uterus.
Not every egg obtained will be mature enough in order to be fertilized, not every fertilized egg will develop into a pre-embryo and not every pre-embryo will invariably implant in the mother's uterus after embryo-transfer.
In general terms, the pregnancy rate in patients under 35 years old using their own eggs is between 40 and 50%; for patients between 35 and 39 years old it is 30%, and after 40 years old it is 15 to 20%. After 42 years of age, pregnancy rates are very low.
WHAT HAPPENS IF PREGNANCY IS ACHIEVED?
When pregnancy is achieved as a result of an assisted reproduction treatment, the chance of reaching full term is the same as for those conceived spontaneously. It is false that IVF or ICSI "enhances" embryos, they only allow fertilization to take place.
