What is IVF and ICSI ?
IVF and ICSI are the methods of assisted reproduction in which human sperm and eggs are combined outside the human body in a laboratory dish. The result of this combination is a fertilized egg that will go on to develop into an embryo. One or more embryo may be transferred into the uterine cavity for implantation. The excess embryos may be frozen for future use.
The basic steps of IVF and ICSI treatment are ovarian stimulation to produce several eggs, fertilization, embryo culture, embryo transfer and freezing the remaining embryos.
The difference between IVF and ICSI is the fertilization technique that is used. In the case of normal sperm quality, in vitro fertilization can be done successfully by putting enough concentration of live sperm into the eggs and waiting for fertilization to occur naturally. In the case of low sperm quality, intracytoplasmic sperm injection (ICSI) will be done instead of IVF. ICSI is the process in the laboratory of selecting one good sperm and injecting it into an egg by the scientist. By doing this, the fertilization can be optimized in the case of low sperm quality that is not good enough for IVF.
Ovarian stimulation program
The first process of IVF and ICSI is reproducing several eggs by using fertility drugs. The purpose of using medication is to stimulate multiple egg growth in the ovaries rather than only a single one that normally develops naturally each month. By doing this, the chances of success will be higher than those of natural conception.
There are several ovarian stimulation protocols used to reproduce the eggs. In our case, we use only one protocol of which we have several years’ experience. The protocol we choose for our patients is the GnRH (Gonadotropin releasing hormone) antagonist protocol. This protocol is easy and can improve the bioavailability of the medication to the patient. The egg quality after the protocol is no different to that of the earlier protocol that was quite difficult for the patient. Our protocol is patient-friendly. There is no need to check blood tests several times or to conduct transvaginal ultrasound over several days. This protocol works for all age groups and all kinds of patients.
Usually we start medication on the second or third day of the period and an appointment is made for our patient for this time. On the second or third day of the period, we will check the hormone profile and AMH levels to evaluate the ovarian function and choose the dose of fertility drugs that is appropriate for each patient. Transvaginal ultrasound is not so important for the first visit because AMH can evaluate the ovarian response very well, except where there are some evidences from the hormone profiles that we need to evaluate further with transvaginal ultrasound. However, the follow-up to evaluate the medication response is very necessary. We can follow up the ovarian response after medical injection for a few days to monitor the response by evaluating hormone levels and/or by transvaginal ultrasound and adjust the dose level according to the response. We call this the individualized ovarian stimulation protocol.
Does the dose of medication really correlate to the number of eggs?
No, it does not. A higher dose of medication does not always reproduce a higher number of eggs. The number of eggs depends on the age of the woman, the variation between cycle to cycle, her ovarian function, and ovarian reserve. In the case of over responders (younger women or PCO cases), the dose of medication should be lower than the normal dose to minimize complications of too many eggs and complications arising from over response.
In the normal responder, the dose can be adjusted according to the response. In an older patient or a low responder, the dose can be increased maximally at 300–400 units per day, which is the highest dose that can recover the good-quality egg. In contrast, a dose higher than 400 units, for example 500–600 units per day in a low responder or older patient can damage the egg quality but the number of eggs is not increased. The main reason for this is that too high a dose of medication will aggravate the growth rate and produce abnormal eggs.
The average egg number for each ovarian stimulation can be estimated by transvaginal ultrasound for antral follicle count and AMH level. For our own data, the correlation between egg number and AMH level is very high.
After completion of the ovarian stimulation program, ovulation will be triggered with a new medication that allows the follicles release the eggs. There are a few kinds of ovulation triggers on the market, for example hCG and GnRH agonist. After medication, we need to ensure the effectiveness of medication by testing the blood or urine.
Egg retrieval procedure
The procedure to aspirate the eggs from the follicles under transvaginal guided ultrasound requires general anesthesia to ensure the patient feels no pain and is asleep.
Egg retrieval is accomplished by transvaginal ultrasound aspiration. An ultrasound probe is inserted into the vagina to identify the follicles, and a needle is guided through the vagina and into the follicles.
The eggs are aspirated from the follicles through the needle connected to a suction device. This usually takes less than 30 minutes and depends on the number of eggs. After the procedure, some women may experience cramping on the day of retrieval but usually the discomfort will be better on the following day except for some women who have many eggs who may still experience some lower abdominal discomfort for a few days.
After the eggs are retrieved, they are recovered from the follicular fluid and kept in physiologic media.
After half an hour of recovery in the physiologic media, the eggs will be processed for fertilization with sperm either using the IVF or ICSI technique.
In the case of ICSI, the eggs will have the external shell removed. The denuded eggs are examined in the laboratory for maturity and quality. Mature eggs are placed in an IVF culture medium and transferred to an incubator to await fertilization by the sperm. Normally, the percentage of egg maturity is at 80% or more. For example: 10 eggs can be retrieved, eight of which will be mature enough for fertilization and the other two will be immature. Only mature eggs can be used in the process of fertilization. Immature eggs are usually abnormal and need to be discarded. Not all eggs can be used and not all mature eggs will be normal and lead to a healthy pregnancy.
Sperm is separated from semen usually obtained by masturbation into a sterile container. Specifically, sperm are retrieved from the testes directly by surgical technique due to problems of azoospermia (no sperm in the ejaculate) or a problem of low quality of ejaculated sperm.
Fertilization may be accomplished by insemination whereby enough motile sperm are placed together with the eggs and incubated for a while to await in vitro fertilization or ICSI, where a single sperm is directly injected into each mature egg.
On the day after egg retrieval and fertilization, visualization of two pronuclei confirm fertilization of the egg. One pronucleus is derived from the egg and one from the sperm.
The general fertilization rate of mature eggs varies from 65–75%. The cause of a lower fertilization rate in the hands of an experienced embryologist may be poor egg or sperm quality. Occasionally, fertilization does not occur at all, even if ICSI has been used.
This picture confirms that the egg contains one male and one female nucleus (from the father and the mother). Sometimes, we can see that the egg contains more than two nuclei, the extra one being from either the father or the mother. This is an abnormal fertilization and the egg needs to be discarded.
On the following day, the embryo will be divided into two cells, four cells on day 2, and eight cells on day 3. Sometimes we transfer eight-cell-stage embryos to the patient. If we culture the embryo longer and wait for at least five to six days for blastocyst development (fluid-filled cavity formed), we will get the most potent embryo with a higher chance of implantation than the eight-cell stage. Most of the time, we prefer to transfer the embryo at a later stage on day 5. However, the number of embryos that can grow beyond the eight-cell stage depends on egg and sperm quality as well as on the quality control in the embryo culture system.