How IVF works: The procedure step by step

IVF (in-vitro fertilisation) is an assisted conception technique that attempts to artificially induce a pregnancy.

IVF is a multistep process. where the woman’s natural menstrual cycle is firstly supressed (downregulated) and  then artificially controlled by the consumption of various drugs.

The ovaries are then stimulated to produce more mature eggs than the normal one per cycle with injectable medications. When ripe the eggs are then collected with a minor surgery and mixed (IVF) or injected with sperm (ICSI) in a laboratory before embryo(s) are transferred back into the woman.

Additional medications are also given to support the second half of the cycle to optimise the chance of a pregnancy occurring.

Finally, generally a blood pregnancy test will be performed around two weeks after the transfer, and if positive, the medications will need to be taken for up to 12 weeks of pregnancy before the placenta is mature enough to take over.

In more detail:

IVF Procedure – Downregulation

The downregulation phase is designed to suppress natural ovarian activity, usually using the contraceptive pill, so that timing of the menstrual cycle can be controlled.

Additionally to this, the centres in the brain responsible for releasing hormones called follicle stimulating hormone (FSH) and luteinising hormone (LH) that are responsible for stimulating the ovaries to make and ovulate mature eggs in a normal menstrual cycle need to be suppressed. This is because if they were not, inappropriate early ovulation could happen during the subsequent stimulation phase of IVF due to the higher than normal levels of estrogen made by many maturing follicles at once.

To do this a drug of the type known as a GnRh agonist (such as Synarel, which is inhaled like a sinus medication, or Lupron, which is given by injection) is given once or twice daily. This has the effect of causing the brain to release all of its stores of FSH and LH during downregulation, and then keeps them low so that premature ovulation cannot occur.

At the end of the downregulation phase, the birth control pills are stopped, but the Lupron or Synarel continues to be taken. The woman will then have a period, followed by a vaginal ultrasound scan to confirm that the ovaries are suppressed and the lining of the womb is thin.

IVF Procedure – Stimulation

Once the downregulation has been completed, the ovaries will need to be stimulated to produce more eggs than would normally happen in a natural cycle. To do this, artificial forms of FSH are given by injection (they are not absorbed orally, so injection is necessary) daily. This will stimulate the antral follicles (eggs ready to develop into more mature form) in the ovaries to grow, and unlike in a natural cycle where follicles compete for FSH and only the ‘strongest’ is ovulated, many will usually grow.

The Lupron or Synarel from the downregulation phase will also be continued to be taken until the end of the stimulation phase so that premature ovulation does not occur.

The FSH dosage is carefully adjusted based upon either the results of the number and size of the follicles growing in the ovaries on vaginal ultrasound and/or blood tests of the level of estrogen in the blood made by the growing eggs.

Without careful monitoring (especially in younger women with polycystic ovarian syndrome) there is the risk of a potentially serious complication known as OHSS (ovarian hyperstimulation syndrome) where too many eggs are made and estrogen levels are very high.

If OHSS occurs, depending on the severity, the woman may be more closely monitored, or eggs may be retrieved and no embryos transferred (being frozen for transfer in a later cycle after the OHSS has resolved), or the trigger injection may not be given and the entire cycle cancelled.

The duration of stimulation depends on the response to the FSH, but is typically in the range of ten to fourteen days. At the end of this phase when there the follicles are of a mature size an injection of HCG is used to artificially mimic the natural hormonal surge of LH that would occur to trigger maturation of the eggs and ovulation (if the woman had not been suppressed with the Lupron/Synarel).

The timing of this injection is critical, as if it is given too early before egg retrieval the eggs will be ovulated into the fallopian tubes and lost, and if given too close to egg retrieval will not have had time to work and the eggs may not be able to be retrieved or may still be immature. Typically the timing is 36 hours before retrieval, so it is important to follow your clinic’s instructions precisely.

IVF Procedure – Egg Retrieval (ER)

This part of the IVF cycle involves a minor surgery, usually with sedation, where a fine needle is passed through the walls of the vagina and into each ovary under ultrasound guidance to collect the mature eggs.

The eggs and fluid aspirated from each follicle are collected into test tubes and passed directly to an embryologist who will separate the eggs using a microscope and then either mix them with sperm, allowing fertilisation to happen naturally, or if the count is very low or there are other sperm problems single sperm may be carefully directly injected into each mature egg.

Generally the retrieval procedure itself is only fairly minor despite being the most fearsome sounding part of the IVF procedure cycle, taking around half an hour. Once the eggs are retrieved the woman will spend 1-2 hours in the recovery room and then go home. Some cramping and discomfort is common, but it is not usually severe enough to require more than minor analgesics such as paracetamol/acetaminophen.

The day after retrieval, the eggs are examined to determine how many have successfully fertilised, and they are monitored thereafter to see how they continue to divide and help decide the day of transfer.

IVF Procedure – Transfer