IVF description

In Vitro Fertilization (IVF)

The fusion of spermatozoon and oocytes may be prevented by a number of factors. Fortunately, such assisted reproductive technology as IVF can become a support. IVF is a method allowing to conjugate male spermatozoon and female oocytes outside the body, in other words – in vitro (“in the glass” or in the laboratory tube). Then it comes turn for fertilization and derived embryos are placed in the uterine cavity. One or several embryos are implanted into uterine endometrium which gets developed during the next nine months.

Roughly saying, IVF is not a method of infertility treatment but a method of overcoming infertility, as it doesn’t eliminate reasons which have caused infertility. However it allows the doctor in the laboratory to do what the couple couldn’t do in the bed. Thus IVF overcomes the impediments for pregnancy without eliminating its causes.

Initially IVF was used for the treatment of women with impassable, damaged or missing fallopian tubes, e.g. infertility conditioned with the tube factor. But presently IVF helps to overcome almost all reasons of infertility, including endometriosis, male factor and infertility of unknown genesis.

The main phases of the treatment with the IVF method

stimulation of superovulation (maturation of several oocytes during one menstrual cycle),
generation of oocytes through oocyte puncture,
oocyte fertilization in “the test tube”,
cultivation of embryos during 2-6 days in artificial conditions,
transfer of embryos to the uterine cavity.

Stimulation of superovulation

Superovulation is the maturing of several oocytes in one menstrual cycle. However during a natural ovulation only one-two oocytes mature each month. In the program of in vitro fertilization doctors attempt to get several oocytes (10-20) because some oocytes may not get fertilized, some embryos may stop growing. Besides that, the percent of pregnancy cases in the IVF program is higher when more than one embryo is placed in the uterus.

At present in case of IVF hormonal medicines are used for stimulation and control over the superovulation.

Medicines used in ART programs

Medicines for the ovarial stimulation

Human Menopausal Gonadotropin (HMG) (menopur)
Follicle Stimulating Hormone (FSH) (gonal-F, puregon)
Human Chorionic Gonadotropin (HCG) (choragon, pregnil. ovidrel)
Clomiphene citrate (clomid, clostilbegit).

Medicines preventing premature ovulation

GnRH agonists (decaceptil, diferelin, buserelin, zoladex, suprefact)
GnRH antagonists (orgalutran, cetrotid)

Clomiphene citrate, human menopausal gonadotropin (HMG), follicle stimulation hormone (FSH), recombinant FSH and LH, and human chorionic gonadotorpin (HCG) are used for the stimulation of superovulation. Agonists and antagonists of gonadortropin releasing hormone (GnRH) are additionaly used in the ovulation regimen to prevent premature ovulation. In case of premature ovulation oocytes get to the abdominal cavity and their extraction becomes practically impossible.

In VitroMed the type of the stimulating medicine and its dosage is identified individually for each patient depending on the diagnosis, age, efficiency of previous ovulation regimens and other factors. During the first IVF attempt specialists usually prescribe HMG or FSH with the following dosage: 200-200 IU (international units) per day for women below 35, 300 IU for patients over 35 and 150 IU for patients with Polycystic Ovary Syndrome (PSOC) or high risk of Ovary Hyperstimulation Syndrome (OHS). Usually the intake of stimulating medications lasts 8-12 days.

The important point during IVF is the regular control over the growth of follicles for the timely passage to the next phase of the program. The ovary conditions during the stimulation are controlled by trans-vaginal ultrasound, which is conducted on the next day of the follicle development. In most cases the regular ultrasound control is enough for the assessment of the ovary reaction to stimulating medicines and correction of intake doses. Some patients may be assigned a blood test to check the level of estradiol. Normally the level of estradiol in the blood increases parallel to the follicle maturing and the level of progesterone remains low till the moment of ovulation.

Due to the ultrasound examination and hormone test the doctor estimates when the follicles are ready for the puncture. Follicles usually grow for 1-2 mm per day, and the mature follicles have 16-20 mm in diameter. Thus if during the ultrasound examination we see follicles with more than 18 mm in size, we know that the follicle has matured and it’s time for puncture. That will result in the generation of follicular fluid containing oocytes. During the ultrasound examination we also look at the endometrium’s thickness and structure. At the moment of puncture the endometrium should ideally be more than 7 mm thicker and have three-layered structure.

When follicles reach the necessary size HCG is injected. HCG injection allows to control the exact time of the ovulation. Usually that happens 36-40 hours after the injection. The ovary puncture is conducted before the ovulation – usually 34-36 hours after the HCG injection.

GnRH agonists and antagonists prevent LH and FSH release by the hypophysis thus reducing the risk of premature ovulation. However 10% of cycles is interrupted, sometimes even before the HCG injection. The most frequently met reason of the cycle interruption is the bad ovary response to the stimulation. If less than 3 follicles mature in ovaries and the level of estradiol is low, chances for pregnancy are extremely low and based on the agreement by the patient the medicinal cycle is interrupted. The problem of poor ovary response to the stimulation is frequently met in cases of women over 35 and women with operated ovaries, i.e. patients who have low follicle reserves in ovaries. As a result of low follicle quantity the FSH level in the blood is increasing. This group of patients has the lowest chances to get pregnant with IVF program. Based on the initial FSH level in the blood the doctor defines the medicine dose for the ovary stimulation and that why it’s important to check the level of this hormone before the stimulation start.

The poor ovary response to the stimulation in the cycle of in vitro fertilization usually upsets patient because, as a rule, they totally haven’t been prepared for that. The most of women expects that they will have a lot of matured oocytes and they become extremely upset when that doesn’t happen. However bear in mind that this doesn’t mean that the treatment won’t help you. This simply means that the stimulation regimen during the next medicinal cycle will need to be changed. The doctor will probably change the stimulation regimen and will increase FSH or HCG dose and this frequently results in better ovary response in case of younger women.

The other reason for the cycle cancelation can be too high quantity of matured follicles. Usually this can be observed in cases of patients with PCOS. If the patient has more than 25 matured follicles or if the level of estradiol in the blood is higher than 6000 pg/ml (pictogram per milliliter) the cycle is usually canceled to reduce the risk of the severe form of Ovary Hyperstimulation Syndrome (OHS). The alternative to the cycle interruption is the puncture of oocytes and freezing all generated embryos. This gives a chance to save the IVF cycle. If the embryos are not transferred to the uterine cavity, the risk of OHS severe form considerably reduces, as the stimulus for OHS is the pregnancy. The embryos can be unfrozen later and transferred to the patient’s uterine cavity thus increasing chances for pregnancy.

In case of the severe form of OHS specialists conduct a puncture of one ovary 12 hours after the HCG injection with a view to remove the fluid from ovaries filled with oestrogens. The puncture of the second ovary is conducted 36 hours after the HCG injection to generate mature oocytes. This strategy allows to essentially reduce the cases of OHS severe forms among patients without canceling the cycle of in vitro fertilization and transfer of embryos.

Generation of oocytes

Generation of oocytes is usually conducted through the aspiration of the follicle content with trans-vaginal puncture controlled by the ultrasound. It’s a minor surgical operation without any hospitalization.

Usually the puncture is conducted with local or short-term (10-20 minutes) general anesthesia. A trans-vaginal ultrasound sensor is placed in the vagina which visualizes the mature follicles and a thin needle is introduced to the follicle through vaginal wall. Oocytes are aspirated from follicles through the needle. The puncture of follicles usually lasts less than 30 minutes. It’s recommended to have a rest in the ward for 2-3 hours and then the patient can go home. Some women experience painful spasms on the puncture day, but on the next day these feelings disappear. The feeling of spreading or pressure in the abdominal cavity may continue during a few days after the procedure.

In vitro fertilization of oocytes and cultivation of embryos (embryological phase of IVF)

After the follicle puncture the follicular fluid containing oocytes immediately goes to the embryological laboratory. The fluid is examined by the embryologist with the microscope. As a result oocytes are separated. Oocytes are surrounded with small trophic cell cumulus which feed the oocyte. Each oocyte complex with such cumulus cells is washed in a special medium. Aftermath the ripeness of oocytes is assessed. Then they are placed in the special nutritional medium and transferred to the incubator where their fertilization with spermatozoa takes place.

During the follicle puncture the patient’s husband collects sperm in a sterile container through masturbation. Some men experience difficulties during sperm collection because of a great stress and “obligatoriness” of the procedure. They should inform the doctor about that in advance. Such men can resort to initial cryopreservation of sperm which can be later defrozen on the day of the follicle puncture and used in the IVF cycle.

After the sperm collection spermatozoa are washed which allows to select the most mobile and morphologically normal spermatozoa. The definite quantity of mobile spermatozoa (usually 100.000 spermatozoa per ml) is mixed with oocytes (this procedure is called “fertilization in the test tube”) and placed in the incubator. As a rule, permeation of the spermatozoon into the oocyte takes place during a few hours. Fertilization is usually conducted 2-6 hours after the follicle puncture.

The incubator ensures the constant level of carbonic acid, temperature and humidity. The conditions of the incubator and the composition of the nutritional medium imitate the conditions in fallopian tubes thus creating maximal favorable in vitro conditions for embryos. The nutritional medium has a high level of heavy metal cleaning capacity and contains ingredients such as proteins, amino acids, pyruvate, salts, sugar and a special acidity buffer creating optimal conditions for the embryo growth and development .

When a low percent of fertilization is expected in case of IVF standard procedures (e.g. in case of low quantity of mobile spermatozoa in the ejaculate or low percent of fertilization during previous IVF attempts) special micromanipulation methods are applied. Intracytoplasmatic Sperm Injection (ICSI) is the most frequently used method when a single spermatozoon is injected immediately into the oocyte for its fertilization. For more details on ICSI please click here.

In general the percent of pregnancy and the percent of delivery after ICSI is comparable with the results of the traditional IVF. If man has hereditary pathologies causing infertility, which can be transferred from father to son, a medical-genetic consultancy is recommended before ICSI.

18 hours after mixing spermatozoa with oocytes or ICSI the embryologist checks how many oocytes have been normally fertilized. Normally fertilized oocyte (zygota) is a one cell with two pronucleuses. Pronucleuses look like small transparent vesicles within the cell. One of them carries the father’s genetic data, the second one – mother’s data. When they interflow a new life with unique genetic data will be formed. Oocytes with anomalous fertilization (e.g. containing 3 pronucleuses instead of 2) as well as unfertilized oocytes will not be used in future.

The percent of fertilized oocytes is a biological variable which, unfortunately, can’t be fully controlled. In some cases fertilization doesn’t take place even with normal oocytes and spermatozoa. However 50-90 % of ripened oocytes normally get fertilized after IVF or ICSI. The low level of fertilization is observed in cases when spermatozoon or oocyte are of poor quality. The lack of fertilization can also be conditioned with the pathology of spermatozoa’s fertilizing capacity or pathologies of the oocyte.

Normally the fertilized oocytes are cultivated. They start partitioning and their quality is assessed 24 hours later. Embryos are assessed based on their look and the partitioning speed. Embryos of good quality are partitioning quite fast.

On the third day the embryo contains about 6-10 cells. On the fifth day a cavity with fluid is formed within the embryo. Cells are differentiated into two types: cells which will eventually form a fetus, and cells which will form placenta. At this phase the embryo is called blastocyst.

Transfer of embryos to the uterine cavity

Usually the transfer procedure is painless, as it doesn’t require cervical dilatation although some women experience spasms and they may need sedatives. With the help of the simple vaginal mirror the doctor gets access to the uterine neck. Catheter for the embryo transfer is a long, thin, sterile and silicone tube with the syringe on one end. The diameter of the catheter is 1-2 mm. Catheter is filled up with the nutritional medium containing one or more embryos. The doctor smoothly inserts the tip of the catheter to the uterine cavity and injects the medium with embryos. As a rule the transfer of embryos is conducted under the ultrasound control and the doctor can see on the monitor how the medium moves in the uterine cavity.

Many foreign researches have showed that there is no need for recumbent position for more than 10 minutes as that doesn’t influence on the pregnancy. If the embryo is already in the uterus, it can’t “fall out”.

In spite of its simplicity the transfer of embryos to the uterine cavity is the most responsible and critical phase of the in vitro fertilization cycle. The literature provides details indicating that during the transfer up to 30% of embryos may disappear. The success is considerably conditioned with the availability and the consistence of the cervical mucus. E.g. the catheter may stick to the catheter inside or outside or can be pulled out by the catheter to the neck of the uterus. VitroMed has developed a special protocol for the embryo transfer allowing to prevent such situations.

Usually 1-3 embryos of good quality are transferred on 2^nd-5^th day after the puncture. The embryologists have developed a special scale for the assessment of embryo quality. Such quality scale is based on the appearance (morphology) of the embryo in general, as well as its separate cells and intracellular structures (cores, nucleolus etc). But even this doesn’t allow to make an exact forecast. Frequently the transfer of two morphologically equal embryos results in а monocyesis. It’s still a mystery which of these embryos gave a start to this pregnancy or why this one, and not the other one (as they have been placed in the same endometrium).

Sometimes we have embryos of medium or poor quality. Chances for pregnancy in case of transfer of embryos of bad quality are low, but if we succeed in achieving pregnancy the future child will be totally healthy. Therefore the embryo morphology doesn’t always reflect its genotype and development potential. Besides that embryos with genetic pathologies can’t be implanted into the uterus, or the pregnancy will be interrupted in the early period (during first 3 months).

The question on how many embryos to place in the uterus is still one of the most difficult ones faced by the doctor and patient during IVF. More embryos are transferred, more chances for the pregnancy we have. If the main goal of IVF is to achieve a pregnancy, why shouldn’t we transfer all available embryos? However the price of transfer of several embryos is the risk of multiple pregnancy which may cause severe complications both for mother and fetus. The problem becomes more complicated as each embryo may be divided into two embryos resulting in the birth of so called monogerminal twins. To decrease the risk of multiple pregnancies VitroMed clinic practices the transfer of 2 embryos. In exceptional cases and based on indications 3 embryos are transferred.

After IVF

Transfer of embryos is the last phase in IVF cycle and after that the doctor prescribes remedies to “support the lutein phase” which increase the implantation probability and may include medicines, such as oestrogens, progesterone or HCG. The post-transfer period is the most complicated part for patients because of uncertainty and high tension while waiting for the response to the question whether they have got pregnant or not. The pregnancy is defined by a special test measuring the content of HCG hormone in the blood conducted 10-14 days after the transfer. This hormone is only synthesized with the embryo cells.

After the embryo transfer patient are recommended to avoid hot baths, heavy physical loads and sexual intercourses. However women can enjoy their habitual lifestyle and if necessary go back to work on the next day of the transfer. Some patients decide to spend these two weeks in bed. You can do this to be sure that you have done everything possible even if you haven’t got pregnant. But bear mind that your normal physical activity won’t influence on your chance to get pregnant.

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