ART – what?

ART stands for Assisted Reproductive Treatment. This is the general term for the different fertility treatments: artificial insemination, IVF, IVF-ICSI, IVM, etc.

If spontaneous natural conception is proving difficult, various ART treatments are available.
  • We already talked about artificial insemination (IUI) under Insemination and stimulation.
  • But sometimes IUI is not appropriate or does not lead to pregnancy. Then IVF (with or without ICSI) may provide a solution. 
    In IVF/ICSI, fertilisation (the fusion of sperm and egg) does not take place in the woman's body, but in a petri dish in the laboratory ('in vitro' means 'in glass'). The embryos form in this dish, hence the name 'test tube baby'.
  • An extra treatment that becomes possible after IVF/ICSI is FRET, an embryo transfer with thawed embryos.
  • And then there is in-vitro maturation (IVM), a patient-friendly treatment yielding increasingly better results.
    IVM allows in vitro-development of embryos after collecting immature eggs and maturing those in the lab (so also in vitro).

IVF-ICSI step by step


Sound advice

What can I do to give my treatment a greater chance of success? Read it all here.

And click Folic acid if you want to know what every woman who wants to be pregnant should know about it.

Preliminary examinations
Start date ovarian stimulation
Daily Patient Monitoring (DM) 
Pre-operative blood test

Throughout your treatment you receive professional support by people of the CRG team. On the one hand this is of course the fertility doctor, but you can also talk to a counsellor. This is the nurse or midwife who provides information about the treatment, and provides support.

Preliminary examinations       

Because both men and women play crucial roles in reproduction, they will both be subject to a variety of medical examinations. These examinations are discussed at the first appointment with the CRG doctor.
  • For an efficient consultation, it is important you fill out a questionnaire about your medical and family history. The form can be downloaded here: questionnaire woman, questionnaire man
  • To avoid unnecessary examinations, please provide the results of any previous examinations and all relevant medical information. 
  • If this information is elsewhere you can request it. Current legislation allows you to make this request yourself. You can request a copy of your medical record, regardless of whether it is with your GP, gynaecologist or the hospital where you were treated.
  • Any examinations deemed necessary by the doctor can be performed at UZ Brussel or elsewhere:

Preliminary blood test     


Read more about the where-when-and-how of blood samples during your treatment at the CRG.

Every fertility treatment at the CRG is preceded by a blood test. This allows us to establish detailed information regarding hormonal balance, to determine the structure and number of chromosomes and detect possible antibodies for, among others, jaundice (hepatitis), the HIV virus (aids) and syphilis.
Women are also checked for immunity against Rubella (German measles) and toxoplasmosis. Both of these conditions can lead to serious damage to the child during early pregnancy.

Sperm analysis     


Read more about the where-when-and-how of providing a sperm sample.

A man's fertility is determined mainly by the number of sperm present in his semen, their motility and form. That is why all three of these elements are studied in depth: see routine sperm analysis. We check immediately whether sufficient usable sperm can be separated for the insemination or fertilisation of eggs in the laboratory.
If at the time of the medical examination you have not had an ejaculation for three to five days you can immediately produce a sample. Simply by masturbation in a separate room, possibly aided by your partner.
The sample may also be produced elsewhere than the CRG, provided that it is delivered to the lab within an hour in a special container. For this, you have to make an appointment with the andrology lab beforehand (see contact). The container must be kept at body temperature, e.g. by putting it in the inside pocket of your coat.  

Other tests   

Depending on your specific medical situation other tests or procedures may be necessary. See the overview for men and women.


About five weeks after the first doctor's consult all preparatory tests have been carried out and the results are known. This is followed by your second appointment with the doctor, during which he/she goes over the results with you. Based on this the doctor suggests treatment.
You will then have an appointment with the counsellor for an information session during which your treatment is discussed from various angles. The counsellor will discuss the following with you:
  • the practical aspects, such as the start date and the consultation with the planning coordinator, opening hours, the process for making appointments at the CRG, where and when, which procedure takes place, etc.
  • the medical side: what your treatment involves, which medication you will be taking, how you should administer it and how you should prepare for a procedure; 
  • the communication with the CRG: with the Centre's Daily Patient Monitoring department (DM) during your treatment, and with the follow-up team afterwards in case of a pregnancy; 
  • the legal aspects, such as consent forms you have to sign; and 
  • the financial side of the treatment with information on the reimbursement conditions for Belgian patients with national health insurance.

If the doctor has not yet done so, the counsellor will advise women to start taking folic acid as soon as you decided to start fertility treatment. See folic acid for the why.

During the entire treatment, the counsellor will be your confidential adviser whom you can contact at any time during office hours for advice and information. Thanks to his/her vast experience, your counsellor will be able to guide you through any practical, physical or psychological problems. If necessary, your counsellor will make additional appointments for you with your doctor, or with the psychologist at the CRG. She (or he) will also be there to help you through additional ART attempts.
For some aspects of your treatment, you will be on the VP03 ward at the CRG. The role of counsellor will temporarily be taken over by the nursing staff on the ward.

Agreements on the start date of ovarian stimulation     

General rule

In all cases when the start date has not yet been laid down during the consultation at the CRG or needs to be changed for some reason: contact us for a specific date as soon as you have made the decision. Please contact the planning coordinator for this (see contact)
The longer in advance you do this, the greater the chances of starting the treatment on the date you want to.

There is a very important date on the medication scheme of the IVF treatment, i.e. the date on which you (the woman) start the hormonal stimulation phase of the treatment. We refer to this date as the start date. As long as it has not been scheduled, your treatment has not been included in the CRG's planning and therefore cannot be started.


IWe want to guarantee the very best quality for every IVF treatment at our centre. This is why we take great care to support our patients - you and your partner - but also the actual in-vitro fertilisation, i.e. the laboratory work.
Quality standards and control procedures need to guarantee the best possible lab results. But quality costs time. There is a limit to the number of actions that the embryologists, nurses and doctors are able to carry out in a day. And this is why a strict planning is required based on the start date of the ovarian stimulation. All the next stages of the treatment are based on this date.


  • If this is your first IVF treatment, the start date is agreed during your interview with the counsellor and will be specified on your treatment plan.
  • If the treatment is unsuccessful and you wish to start a new treatment cycle, a new start date will be chosen by you, your gynaecologist and counsellor. For medical and organisational reasons often it won't be possible to immediately start the next menstrual cycle.

In both cases you may not immediately decide with the counsellor or the gynaecologist to start with the (new) treatment. In this case a provisional start date is usually agreed.
  • As soon as you have decided to start a (new) IVF cycle, you will need to confirm this start date before you start taking the stimulation medication again.
  • The same applies when you interrupt your treatment. Sometimes the ovarian stimulation does not give the desired result and is therefore terminated. For reasons of quality it is often decided therefore to skip a cycle before starting again.
    Again, a new start date needs to be agreed and your treatment rescheduled.

In short, if a start date has not been laid down in joint consultation between you and either your counsellor (during a first treatment) or your gynaecologist (at the next attempts) there is no point to start taking the stimulation medication. Because, if you have not agreed on a start date, your treatment will not have been scheduled.
Determining or changing a start date (later) needs to be done in consultation with the planning coordinator.

Daily Patient Monitoring department (DM)   

Hormonal tests and ultrasound scans are an inextricable part of ART:
  • hormonal analysis of blood samples allow us to check and adjust the treatment, 
  • ultrasound scans allows us to see whether there are any ripe follicles in the ovaries.
The department of the CRG which coordinates and communicates the results of these tests is called the Daily Patient Monitoring department (DM).
For the most part of your treatment, you will be in daily contact with this department: they call you with the results of the tests and with instructions about the continuation of your treatment.

Pre-operative blood test     

Egg retrieval, the procedure whereby the ripe eggs are collected, is usually done under a local anaesthetic and does not require pre-operative blood tests.
However, if it has been agreed that the procedure needs to be done under general anaesthetic, due to either personal choice or medical reasons, pre-operative blood tests will be required (see blood tests).

Body's own hormones
IVF preparations

During IVF treatment, hormones are used which, albeit under different circumstances, are also produced by a woman's body.

Body's own hormones       

  • GnRH (gonadotrophin releasing hormone) is made in the hypothalamus. It triggers the release of LH and FSH (sex hormones or gonadotrophins);
  • Gonadotrophins are released by the hypophysis, also in the brain. Via the blood they work on the reproductive organs:
    • FSH (follicle stimulating hormone) triggers the development of follicles in the ovaries;
    • LH (luteinising or ripening hormone) triggers ovulation.
  • Oestrogens and progesterone: female hormones.
    They are produced in the reproductive organs, each in a different phase of the menstrual cycle and in different quantities.
  • hCG (human chorionic gonadotrophine): pregnancy hormone. It is produced by the placenta and indirectly supports pregnancy. Presence of this hormone in a woman's blood is evidence that she is pregnant (pregnancy test).
  • hMG ((human menopausal gonadotrophine) is found in the urine of women going through the menopause. It contains both LH and FSH in high doses.

Want to know more?

Is hormone treatment harmful?

IVF hormone preparations       

In IVF, various hormone preparations are used, both for the suppression of the natural cycle and the stimulation of the ovaries.
For the suppression of the natural cycle      
  • Agonists have the same effect as GnRH.
    GnRH, which is produced by the hypothalamus, breaks down quickly (short half-life). This hormone, produced naturally by the body, was isolated and identified in the seventies. 'Analogues' (synonym agonists) were sought to imitate it.
    Agonists are therefore GnRH analogues: hormones with the same effect, but with a longer half-life.
    In large doses, they ensure the increased secretion of FSH and LH, which depletes it. This suppresses the natural cycle and prevents ovulation.
  • Antagonists suppress the production of LH.
    Antagonists are the result of later clinical developments. Because they stop the release of LH, this medication also suppresses natural ovulation. Ovulation can then be triggered when required for the treatment.
For the ovarian stimulation      
The ovaries are stimulated, either shortly afterwards or at the same time with hormones which simulate the effect of FSH (and LH).
Gonadotrophine preparations (hMG or rec-FSH) trigger the development of several follicles simultaneously. The administration is carried out under strict hormonal and ultrasound control, to avoid over stimulation.
The hMG used during IVF treatment is produced from human urine from women going through the menopause. It is a combination of FSH and LH and when administered in the correct dose has the same effect of (administered) FSH. However, it is currently not available on the Belgian market.
rec-FSH: a synthetic (recombinant) substitute for FSH.
To trigger ovulation      
Every kind of stimulation treatment ends with an hCG-injection. hCG or pregnancy hormone can be obtained from purified urine from pregnant women. Administration of the hormone has the same effect as LH. It results in ovulation 36-42 hours later.

To support pregnancy     
A resulting pregnancy is supported:
  • in most IVF treatments via the administration of natural progesterone. This hormone assists in the development of the lining of the womb and facilitates the implantation of the embryo;
  • in some cases, the uterus is prepared for the transfer of a (thawed) embryo via the administration of oestrogen.

Day 1 of your cycle

Day 1 of your cycle is the day you get up with bright red menstrual blood loss.
If your period starts during the day or the blood only turns bright red over the course of the day, the next day applies as day 1.

Applicable for every medication scheme
Long procedure with agonists
Short procedure with agonists
Procedure with antagonists
Without suppression

Ovarian stimulation is possible in various ways.
  • In most patients the natural menstrual cycle is suppressed together with the stimulation.
    This can be done before the start of the stimulation or at a later time.
  • Remember

    ART is individual.

    Sometimes your cycle is adjusted beforehand with a contraceptive pill for better planning and monitoring.
  • And sometimes it is not suppressed: the stimulation is tuned to your natural cycle.
The decision of which option to use depends on the specific medication scheme the CRG doctor thinks is most appropriate for you. Some things are the same for every form of treatment.

Applicable for every medication schedule         

  • Practical

    Read more about the where-when-and-how of blood samples during your treatment at the CRG.

    Before starting any suppression or stimulation medication, the start date of your ovarian stimulation needs to be determined. See IVF|ICSI start stimulation.
  • All injections are given subcutaneously (under the skin).
  • Blood samples measure the levels of hormone in your blood which the DPM puts in a diagram. They will call you with instructions regarding the doses to be injected.
  • Once oestrogen levels in the blood begin to increase and the moment of ovulation nears, regular ultrasounds are carried out.


    Read more here about the where-when-and-how of the ultrasound.

    The development of follicles can be monitored with these ultrasounds. This allows us to determine the best moment for egg retrieval.
  • The number of ultrasounds and blood tests depend on how well your body reacts to the stimulation.

Possible side effects
  • The medication causes several follicles to develop at the same time and the ovaries increase in size. This may cause some discomfort and lead to light abdominal swelling.
  • The injection of hCG can cause local irritation and redness around the injection sites.

Long procedure with agonists     

Phase 1 - Suppression of the natural cycle     
  • Either on day 1 or on day 21 of your natural cycle, approximately three weeks from the planned start date of stimulation, the suppression of your cycle will start with the administration of GnRH analogues (see used hormone preparations).
  • That same day, you must have a blood test. You will have several more blood tests during the following weeks to monitor the effect of the medication.
  • Before the start date of the stimulation, an ultrasound scan will be performed to check for the presence of ovarian cysts (fluid-filled sacs). If so, a decision may be made to remove them first because some of these cysts also produce hormones.


Throughout the stimulation, i.e. up to the hCG-injection, you need to take the GnRH-analogues.

GnRH-analogues are administered in a simple way. They are available in the form of a nasal spray.
  • During the day, every three hours approximately, you need six times one inhalation alternating between nostrils.
  • You need to do this every day. You don't need to get up in the middle of the night to do this: once before bedtime and again first thing in the morning is sufficient.
Daily or monthly GnRH analogue injections are sometimes used as an alternative to the nose spray.

Possible side effects
As a result of the large doses of GnRH analogues, the hypophysis will increase production of FSH and LH until its supply is exhausted. As a result, no stimulation impulse will be sent from the brain to develop and ripen any eggs. This stimulation comes (at a later stage) from the injection of hMG or rec-FSH and hCG, which work directly on the ovaries.
In fact, the agonists cause an artificial menopause, which is accompanied by typical menopausal symptoms such as hot flushes, irritability and headaches. Irregular vaginal bleeding may also occur.
The side effects are unpleasant, but fortunately they are only temporary and not dangerous. They disappear as soon as ovarian stimulation begins.


Avoid hMG or rec-FSH injection mistakes.

Phase 2 - Ovarian stimulation       
  • On the evening before the planned start date of the stimulation, once the blood tests confirm that the natural cycle has been fully suppressed and ultrasounds reveal no presence of ovarian cysts, the DPM will call you that the stimulation phase may begin.
  • During the stimulation, which usually lasts for about ten days, you will need an injection of hMG or rec-FSH. This is under the skin (subcutaneous).

Short procedure with agonists       


Make sure you can be reached.

Sometimes the suppression of the natural cycle with GnRH-analogues is combined from the start with ovarian stimulation. This short procedure always starts on day two of your menstrual cycle.
  • On day one, you will have a blood test.
  • On day two you start taking GnRH-analogues (suppression).
  • On dag three you start the injections with hMG or rec-FSH (stimulation).
From now on the procedure is as previously described: blood tests, ultrasound scans and the DPM which tells you which doses to administer.

Procedure with antagonists        

The use of so-called 'antagonists' allows a shorter treatment method, with fewer injections. Antagonists cause the hypophysis not to release any LH which suppresses natural ovulation.
  • This procedure begins on day two of the natural cycle, without prior suppression of the natural cycle.
  • On day one you have a blood test.
  • On day two you start with the injection of hMG or rec-FSH (ovarian stimulation).
  • At a preset time - sometimes at the same time, but usually after five days - you start administering antagonists (suppression of your LH-production to prevent spontaneous ovulation).
Like with the other stimulation methods, you need to follow the DPM's instructions from now on.

Long procedure      
This protocol is identical to the short procedure, apart from the fact that it is preceded by a period in which you take a contraceptive pill for better control of your natural cycle.
  • On day one of your cycle, you start taking a contraceptive pill which contains at least 30 micrograms of oestrogen.
    This artificial increase in oestrogen levels causes the hypophysis to secrete lower levels of FSH and LH. The ovaries are not stimulated to develop any eggs.
  • You take the pill for at least three weeks. Then you stop.
  • You wait until your period starts and on day two a blood test is performed.
  • At the time specified by the DPM you start with the injection of hMG or rec-FSH (ovarian stimulation).
  • At the same time or a couple of days later (when told by the DPM) you start on the antagonists (suppression of your LH-production, to prevent spontaneous ovulation).

Possible side effect
During the first few days after stopping the pill, you may have some blood loss.

Without suppression     


With this protocol there is a high risk that no embryo transfer will take place.

Sometimes the IVF or ICSI intervention, i.e. fertilisation in the lab, can be totally tuned to your natural cycle
  • Via blood tests we monitor the hormonal development of your cycle, and via ultrasound scans the development of the follicle(s).
  • Sometimes light ovarian stimulation is given either early on in the cycle, or as soon as the follicle has reached a size of 15-16mm (a ripe follicle is >17mm).
  • In the latter case an antagonist is sometimes given additionally to prevent natural ovulation.

If the ultrasound indicates sufficient numbers of well-developed follicles, the DPM gives you the green light for the hCG-injection. This completes the development of the egg and triggers ovulation.
As of this point, you stop with the injections of rec-FSH or hMG (stimulation) and, if this was the case, the use of agonists or antagonists (suppression).

HCG triggers ovulation. That is why egg retrieval is 36 hours after the injection, just before ovulation. The eggs are collected for fertilisation in the laboratory.


    Make sure you can be reached.

  • The DPM determines both the day and the time of the injection.
    To make sure egg retrieval can take place during the day, the hCG-injection is given in the evening or at night
  • The injection is given under the skin, at home.

How does egg retrieval work?
Don't forget!
We collect the eggs during an operation in the Operating Theatre, which we call egg retrieval.
  • The DM determines the exact time for the procedure.
  • In the six hours preceding the procedure, you may not eat or drink.
  • In preparation for the operation:
    • you take a shower,
    • you remove all jewellery, rings and piercings, and
    • you remove all make-up, nail polish and/or gel nails on both your hands and feet.

Punctuality is essential

For the egg retrieval you have to be on time: we need to make sure we stay ahead of the ovulation.

How does egg retrieval work?   

  • Two hours before the procedure you are expected at the the CRG's nursing ward, the VPE03, route 972.
  • First you have to sign up at the registration desk. For opening hours, see Registration at UZ Brussel. Then proceed to the VPE03.
  • There you will be given a bed, a theatre gown, a cap and a bracelet with your name.
  • When you've changed you will be given premedication. This relaxes you and contains a pain killer.

Good hygiene

The personnel treating you very much appreciate good hygiene.
A shower or wash before your consultation and clean feet make it more pleasant for everyone around.

In the Operating theatre
  • From the VPE03 you are transported to the CRG's operating theatre where you have to wait for a short time.
    For practical reasons partners are not allowed into the operating theatre during egg retrieval. He or she can wait for you in the VPE03.
  • Blood is taken and a drip is placed to ensure a good fluid balance and any problems during the procedure (nausea, bleeding, etc.) can be swiftly dealt with.
  • A local anaesthetic is injected next to your cervix. 
  • While the anaesthetic starts to work, your vagina is disinfected.
  • Egg retrieval is performed under ultrasound guidance.
    As with all vaginal ultrasound scans, a small probe is inserted into the vagina to obtain an image of the ovaries. You can follow the whole procedure on a screen.
  • The gynaecologist inserts a fine, hollow needle through the vaginal wall, into the ovary.
    One by one, the ripe follicles are punctured and the fluid inside them containing the egg is aspirated via the hollow needle.

After the procedure      
  • You are returned to the VPE03 to rest. After a while, the drip is removed.
  • You're allowed to go home the same day.
  • Meanwhile the eggs have been removed from the follicular liquid in the laboratory. Before you leave the hospital you'll be told how many were harvested.

    Procedure anaesthetic

    How does the UZ Brussel go about examinations or operations under anaesthetic?

    Is egg retrieval painful? Because you are given a local anaesthetic and a general painkiller, the level of discomfort will not be too bad. Some women feel nothing at all, whilst others experience clear but tolerable levels of pain when the ovaries are punctured.
    If you explicitly prefer, the procedure can also be performed under general anaesthetic. This will be in the form of a 'sedation', which just renders you lightly unconscious. With a sedation you feel nothing of the egg retrieval. This light sedation is not harmful to your eggs.
    If you want sedation, you must inform your counsellor or gynaecologist after one week of ovarian stimulation at the latest. If your request comes later, we will be unable to make the necessary arrangements. In the days before the procedure you still need a pre-operative blood test and have an anaesthesia consultation.


    If we do not have the health insurance consent form on the day of egg retrieval, the costs of the treatment (medication and laboratory) will be billed to you in full.

    Don't forget!    

    For the sake of efficiency, it is important you bring the following on the day of egg retrieval:
    • your identification label and your partner's if applicable,
    • if you are covered by the Belgian National Health Service, you must bring the health insurance consent form if we don't have it yet;
    • unused medication does not have to be returned, as the pharmacy will not take it back.

    Fresh sperm sample
    Frozen sperm
    Sperm extraction
    Surgical procedures
    Artificially generated ejaculation

    On the day of the egg retrieval, a sperm sample will of course have to be produced to fertilise the eggs

    Fresh sperm sample      


    Read more about the where-when-and-how of providing a sperm sample.

    Fresh sperm is preferable for in vitro fertilisation. This maximises the chances of fertilisation.
    • For the production of your sample, you need to go to the VPE 03 ward of the CRG.
    • To give the laboratory time to 'prepare' the sperm (take out the most motile sperm), the sample has to be delivered in the morning:
      • the DPM will notify the exact time, but
      • on weekdays this is between 8 a.m. and 11 a.m., and
      • in the weekend between 9 a.m. and 11 a.m.

    Frozen sperm    

    If you are unable to be there on the day of your partner’s egg retrieval, or if you think you won't be able to produce a sample at the crucial moment, you can have a sample frozen in advance (freeze and store). Your partner's eggs will be fertilised with the (thawed) semen, provided the quality is adequate after thawing.
    If donor sperm is used for the IVF treatment, it is always thawed sperm.
    You need to make an appointment with the Andrology Lab to store a sperm sample (see contact).

    Sperm extraction     

    If you have no sperm in your ejaculate you don't immediately have to revert to sperm donation anymore. Specialised procedures exist which often result in the retrieval of useable sperm.
    • If sperm is collected following a procedure, the ICSI-technique (injection of one sperm in every egg) is always used for fertilisation in the laboratory.
    • Thanks to the existence of this technique only a few sperm are required. They don't even have to be fully mature. As soon as they are formed (in the testicle) they contain all your genetic information.
    • For ICSI we prefer to use fresh sperm. Your procedure (see infra) will usually be performed on the same day as your partner's egg retrieval.  
    • The procedure often yields enough sperm for several ICSI sessions. When all ripe eggs have been injected with a sperm, the remaining sperm can be frozen for future treatment.

    Surgical procedures     

    The type of procedure used to retrieve sperm depends on the nature of your fertility problem. See sperm extraction for ICSI for more information.
    • Sperm from the epididymis: MESA or PESA
    • Sperm from the testicle: TESE or FNA.

    Procedure anaesthetic

    How does the UZ Brussel go about examinations or operations under anaesthetic?

    Procedure with anaesthetic?
    • PESA, TESE and FNA can either be performed under local or general anaesthetic.
    • MESA is always performed under general anaesthetic.
    The choice between the various procedures and the type of anaesthetic will be decided by your doctor. The decision will be made based on the results of the preliminary examinations, but also according to what is most feasible in practice in your situation.

    Artificially generated ejaculation      

    For men who are unable to ejaculate, there is the option of vibratory or electrostimulation.
    • Vibratory stimulation is a procedure without anaesthetic.
    • Electroejaculation is performed under general anaesthetic, or if the man's lower abdomen is paralysed, without anaesthetic.

    Classic IVF
    no extra risk
    Life as it is happening (film)
    Strict identification procedure

    This is the essence of IVF: fertilisation (coming together of sperm and egg) does not happen in the fallopian tube (which is the natural situation) but in a laboratory.
    • First the semen is 'prepared' in the laboratory: the best, most motile sperm are selected.
    • A couple of hours after egg retrieval, the sperm are put with the egg cells and placed in an incubator. The incubator mimics the environment found within a fallopian tube; the same temperature, the same atmosphere.
    • A day later, they are examined under the microscope to see whether fertilisation has taken place. If it has, we wait another day to see if the embryos continue to develop.
    • If so their quality is determined.
    • On day three or five after fertilisation, one or two embryos are transferred to the uterus (see embryo transfer).).



    Many eggs don't mean many embryos.

    It is possible that the fertilisation or formation of embryos is less successful and that embryo transfer has to be cancelled. In this case, an appointment with the CRG doctor will be arranged as soon as possible to discuss what went wrong. The doctor will explain what went wrong and what we can do to avoid this from happening again at the next attempt.

    Classic IVF       

    In 'classic' IVF, fertilisation occurs in the lab by putting the woman's eggs with a man's sperm in a culture dish.
    • If successful, one or more embryos will develop.
    • Although fresh sperm is preferred for IVF, this method can also be performed using frozen (and thawed) sperm from ejaculate (not from a procedure).
    When using donor sperm, this is the only way of performing the procedure.


    Since the nineties, a new technique has been available to fertilise eggs: ICSI (pronounced 'iksi') or intracytoplasmic sperm injection.
    This technique was developed at the CRG of UZ Brussel and since then has been successfully applied worldwide
    ICSI is particularly useful for couples where the man is less fertile. If his ejaculate contains too few useable sperm for the classic IVF method, then ICSI can be applied. But even if the IVF method doesn't work, ICSI can be used next time, possibly performing both methods on an equal numbers of eggs.

    Injection of a sperm in an egg
    • Firstly, a suitable sperm is selected under the microscope.
    • This is sucked up with an ultra-thin glass pipette and injected directly into the centre of the egg.
    • The pipette penetrates the egg and the sperm is released. Fertilisation takes place mechanically and only one sperm is required.

    ICSI is a delicate but effective technique.
    • Of all the eggs collected at egg retrieval after hormonal stimulation, 80% are generally mature enough to be fertilised this way.
    • 10% of the ripe eggs are lost with ICSI.
    • Of the eggs that survive the procedure, 70% will develop into embryos.
    • Result: approximately 50% of the eggs retrieved following hormonal stimulation can be used for embryo transfer or freezing following ICSI.
      The chances of embryo implantation, i.e. the chances that the woman will be pregnant is just as high as with classic IVF.

    Want to know more?

    Do ART children have more abnormalities ?

    No extra risk     
    Of the 90 percent of eggs which survive and are fertilised, are any eggs damaged by ICSI? There is nothing to suggest this. The abnormalities in ICSI children are as high, or rather, as low as in IVF children.
    Moreover, a ripe egg is a largely empty structure: the nucleus containing the chromosomes, is located right on the edge. The chance of damage is therefore small.

    Life as it is happening     

    Strict identification procedure     

    Want to know more?

    How can we be sure the transferred embryos are ours?

    An IVF laboratory has an important social function. The quality of our products and services require high demands. And rightly so, if you consider that mistakes would have huge consequences.
    The CRG has an ISO-15189 accreditation, an international quality label for healthcare laboratories that establishes strict requirements for the treatment and identification of eggs, sperm and embryos.
    Read more about the quality procedures at the CRG..

    IVF Witness     
    Reliability is of course a top priority. Both for the fertilisation in the laboratory and the later embryo transfer (possibly with thawed embryos), strict identification procedures are applied. The CRG also uses an automated registration system that identifies patients and dishes with sperm, eggs and embryos during the IVF process.
    • When you start treatment, a personal identification card is created for you with a unique electronic reference.
    • That reference is put on special microchip labels and attached to all dishes and test tubes to store your sperm, eggs and embryos.
    • At the time of egg retrieval the electronic system ensures they are collected in the right culture dishes.
    • The dishes are automatically recognised in the laboratory and linked to your partner's sperm. Now the eggs can be fertilised.
    • When you return to have one (or several) embryo(s) transferred, the system automatically ensures your fertilised embryos are used.
    With this system the CRG takes all the necessary precautions to carefully monitor your sperm cells, eggs and embryos during the entire ART process.

    Step by step
    Possible side effect:
    ovarian hyperstimulation syndrome

    Number of transferred embryos:
    laid down by law

    Supernumerary embryos

    Want to know more?

    How can we be sure the transferred embryos are ours?

    The transfer of the embryos that have developed in the laboratory is performed:
    • either on day three, or
    • day five after egg retrieval.
    The exact day is decided with your doctor or embryologist.
    Sometimes the decision is only made on day three itself: you will be contacted on the day in question when the most optimal moment of transfer has been established.

    Step by step       

    • Good hygiene

      The personnel treating you very much appreciate good hygiene.
      A shower or wash before your consultation and clean feet make it more pleasant for everyone around.

      For the embryo transfer we expect you and your partner. He (or she) will therefore be present during the transfer of the embryos.
    • On the day of the embryo transfer you will be told by phone in the late afternoon (normally after 11 p.m.) at what time you are expected at the CRG. The transfer may be slightly later than planned in which case you will have to wait.
    • Prior to the procedure, sign up at the registration desk. See Patient in UZ Brussel  for opening hours.
    • Go to the nursing ward VPE 03 at the agreed time, route 972. From there you will be taken to the operating theatre.
    • The procedure is very short and is both pain and risk-free.  
      • To access the uterus, a speculum is placed in the vagina.
      • The gynaecologist transfers the embryos (one or two) to the uterus using a fine catheter which is passed through the cervical opening.
      • The procedure requires no anaesthetic.
    • After the embryo transfer you may immediately resume your normal life, including moving yourself by bike, car or airplane.
      This in no way affects the success rate of the IVF attempt.

    Ovarian hyperstimulation syndrome       

    Some women have OHSS or Hyperstimulation syndrome during IVF treatment after the embryo transfer
    The symptoms usually consist of a swollen abdomen accompanied by pain, but at times can be more serious: nausea, vomiting, bad abdominal pain, big increase in weight, breathing difficulties, etc.
    The condition is a result of the hormones administered during the stimulation phase.
    • After ovarian stimulation with hMG or rec-FSH, an hCG-injection is given.
      HCG triggers ovulation, but also stimulates the ovaries further.
    • If a woman becomes pregnant following the treatment, her body will also start to produce hCG.
      And it is very small step from ovarian stimulation to hyperstimulation.
    • Hyperstimulation causes the remains of the follicles that were punctured during egg retrieval, to form into cysts in which fluid collects. This siphons through into other bodily cavities, primarily into the abdominal cavity, and your body’s fluid balance is deregulated.
    Fortunately, hyperstimulation syndrome is not usually severe. The symptoms usually resolve themselves after a while. Rest, restricted fluid intake, a protein rich diet (cheese, meat, fish, etc.) and patience are the main recommendations.
    In the unlikely event of a serious case, where the woman develops problems with rapid weight increase, breathing and urination, the CRG must be informed immediately. Hospital admission may be necessary.

    Number of transferred embryos - laid down by law     

    The number of embryos that can be transferred has been laid down by law in Belgium. See Permitted number of embryos .
    How many embryos may be transferred is depending on:
    • your age (for women); and
    • the number of attempts you have had.
    The aim of this regulation is to limit the number of multiple pregnancies with ART and thus also the health risks for mother and babies.

    Want to know more?

    Does an ART treatment increase the chance of multiple pregnancies?

    In cases where the transfer of more than one embryo is allowed, the decision will be made in joint consultation with you, the CRG doctor and the embryologist. The decisive factors are:
    • the quality of the embryos,
    • how many are available, and
    • your result with previous attempts. . 

    Want to know more?

    Is freezing embryos for later use a good idea?

    Supernumerary embryos     
    If in vitro fertilisation resulted in more embryos than necessary for transfer, supernumerary embryos can be frozen. 
    • You (as a couple) already decided during your counselling session at the start of the ART treatment whether supernumerary embryos would be frozen or not. You did this when filling out and signing the 'Use of supernumerary embryos' contract.
    • If you decided that the supernumerary embryos could be frozen, you will find out in writing how many were suitable for freezing a couple of weeks after transfer.
      To avoid misunderstandings, this information is only provided in writing.
    Progesterone administration
    Awaiting the result
    End of the treatment

    After the embryo transfer comes a difficult two weeks. You have to wait two weeks for a result: pregnancy or period.
    And you have to continue using the progesterone pessaries to support embryo implantation. This hormone encourages the development of the lining of the womb.

    Progesterone administration     

    • Progesterone administration is started the day after egg retrieval.
    • And you can only stop when the DPM instructs you to. If you're pregnant, this can vary from a few weeks to three months.
    • Progesterone is available in two forms:
    • When instructed to use progesterone it is important you take enough. A high dose implies no dangers. Better an injection or some pessaries too many than too few.
    • Please wash your hands before inserting the pessaries to minimise vaginal infections.
    • Because there will inevitably be some vaginal discharge from the inserted pessaries or gel, sanitary towels are recommended.


    Sometimes the progesterone treatment is replaced or supported by the administration of hCG during the first week after transfer. This pregnancy hormone stimulates the production of progesterone in the body itself.
    If it is prescribed, you will have
    • either one injection of 5,000 units,
    • or a dose of 1,500 units every day on three different days.
    The choice of administration depends on the results of the hormonal blood tests.

    Awaiting the result     

    About two weeks after embryo transfer we can determine whether you are pregnant.
    • On day 12 after embryo transfer you will have a blood test:
      • to verify the progesterone content;
      • to check for possible hyperstimulation; and
      • to measure the hCG-levels.
        The measurement of the hCG-level is a pregnancy test. This test allows us to determine whether you are pregnant or not. 
    • If during these two weeks your period starts, you must provide a blood sample on day three.
      Please don't forget this despite your disappointment.

    End of the treatment      


    Immediately try again after an unsuccessful attempt? It is best to wait.

    After the embryo transfer you make an appointment with the CRG doctor. Usually you will know before this appointment whether or not the treatment has been a success.
    • If you are pregnant, the first days or weeks the DPM department monitors you via blood tests and ultrasound scans.
      But from a strictly medical point of view, your file at the CRG can be closed.
    • If the treatment was not successful, it may be hard to accept. Many couples blame themselves and ask what they did wrong. Mostly, the answer will be 'nothing'. Because apart from meticulously following all the instructions of the DPM there is nothing you can do to influence the result.

    Follow-up during pregnancy and after birth
    If IVF/ICSI treatment was successful, your pregnancy will be monitored:
    • with an ultrasound, five weeks after the embryo transfer;
    • and with blood tests:
      • twice a week up to the sixth week of pregnancy,
      • once a week from the seventh to the twelfth week; and
      • every two weeks if you need to take supporting medication;
    • in the sixteenth week all pregnant patients have a blood test for trisomy 21 (Down's syndrome). This can done at the UZ Brussel or your own gynaecologist.
    From a certain moment your pregnancy will be monitored by your GP or the gynaecologist who referred you to us.

    Follow-up studies at UZ Brussel       

    However, UZ Brussel wants to know about the further progress of your pregnancy and will stay in contact even after birth.
    • We will send you two questionnaires:
      • the first is sent at the end of the first term of your pregnancy;
      • the second after the estimated delivery date.
    • Your counsellor will also contact the Centre for medical Genetics (CMG) at UZ Brussel as soon as pregnancy has been established.
      He or she will inform them of your pregnancy to plan the postnatal examinations of your child, which will take place two months and one year after birth.

    Our questionnaires are, on the one hand, out of personal interest: we like to know whether the treatment was a success and whether you experienced any problems.
    On the other hand they are also part of the scientific study we conduct into pregnancies and children resulting from fertility treatment. The aim is to improve the quality of our treatments and to map the effects of certain changes (e.g. in stimulation medication).
    We also have to meet legal obligations regarding the collection of statistical data on (the health of) our patients and their babies born from IVF/ICSI or AI(D).

    So please do fill out and return the questionnaires.
    Not only does it help scientific research, it also helps future patients. And one day you may be one again.
    Do not worry about any privacy issues because all data is processed completely anonymously. There is absolutely no chance that medical or other information you provide can be traced back to you personally.