In vitro fertilisation
What is In vitro fertilisation (IVF) ?
It is an assisted reproductive technology that involves the fertilisation of gametes (oocytes and spermatozoa) in vitro — in other words, in the laboratory — and the subsequent transfer of the embryo or embryos to the woman’s uterus.
When is in vitro fertilisation recommended?
- After the failure of previous attempts at artificial insemination.
- In case of the absence (or damage) of the fallopian tubes..
- In patients with an advanced maternal age.
- In case of advanced endometriosis.
- In cases where there is a low sperm count.
- In cases of sterility due to unknown causes.
What is the IVF procedure like?
It is a treatment that consists of different stages:
- Controlled ovarian stimulation
- Follicular aspiration (oocyte retrieval)
- Fertilisation of the oocytes
- Embryo transfer
- Embryo cryopreservation
What is controlled ovarian stimulation?
To improve the chances of pregnancy, controlled ovarian stimulation is carried out in order to increase the number of oocytes, with the aim of obtaining a significant number of embryos. Those with the highest quality can be selected for transfer.
It is a hormonal treatment that stimulates the growth of various follicles at the same time, together with the maturation of the oocytes that they contain. This is extremely important as we need to calculate the most appropriate dosage for each woman, taking into account her age, ovarian reserve and medical history, together with other factors. The medication is administered subcutaneously on a daily basis, always at the same time of day.
Testing is needed throughout the stimulation process (including ultrasound and hormonal tests) to ensure that the size and number of the growing follicles is as it should be at each stage. We aim to simplify the process as far as possible, so that it does not impact on daily activities and you can continue with your day-to-day life.
When the majority of the follicles have reached optimal size and the oocytes within can be collected, follicular aspiration is scheduled.
What is ovarian or follicular aspiration?
The aspiration of the ovarian follicles is a minor surgical procedure carried out under sedation (superficial general anaesthesia). This procedure does not require a hospital stay. It is performed through the vagina under ultrasound guidance.
During the procedure, the follicles that have developed by stimulation are aspirated, and the liquid obtained is collected to isolate the oocytes. The picked-up oocytes are placed on a petri plate and then in an incubator that has the optimal conditions for their maturation until fertilization.
On the same day that the oocytes are collected, the male partner needs to provide the sperm. In some cases cryopreserved sperm may be used, or sperm from a sperm bank.
In all of these cases the sperm is processed in the laboratory in order to collect those of the highest quality which will be used to fertilise the oocytes.
How are the oocytes fertilised in the laboratory?
The two techniques used are:
- Standard in vitro fertilisation: a quantity of high quality sperm is added to the petri plate containing the oocytes,with the aim to achieve the spontaneous fertilisation of the oocytes. This procedure is only used when the sperm is within the normal range, and in certain cases of female infertility.
- Intracytoplasmic sperm injection (ICSI): is used in cases where the sperm is at the lower end of the normal range, or is clearly pathological. Using a micropipette, a spermatozoa is injected into each of the mature oocytes — those oocytes that are ready for fertilisation. ICSI is carried out in most treatments in order to obtain optimum results.
In both cases, between 70% and 80% of mature oocytes are fertilised.
How do we know that the oocytes have been fertilised?
Between 17 and 20 hours after the procedure previously described, the oocytes are examined in order to check whether or not they have been fertilised (by inspecting two of the pronuclei), and to reject those oocytes showing abnormal fertilisation, or that have not been fertilised.
The patients are informed of the results of the fertilisation process, and if applicable, embryo transfer is scheduled — this can be done between two and five days after the aspiration procedure.
What is the embryo transfer?
In the embryo transfer, the selected embryos are transferred into the woman’s uterus. The number of embryos to be transferred varies depending on factors such as age, the duration and causes of sterility, previous pregnancies and especially, on the quality of the embryos. The maximum number of embryos that can legally be transferred is three.
The embryos are transferred to the uterus using a catheter assisted by ultrasound. In most cases this is a simple, painless procedure, so the woman can be accompanied by her partner and can follow the procedure via the ultrasound images.
What is embryonic cryopreservation?
Embryonic cryopreservation is a technique that allows the preservation by freezing of the extra embryos produced in the IVF cycle for later use.
Cryopreservation increases the chances of success in cases where pregnancy has not been achieved after the transfer of ‘fresh’ embryos, or enables another, later pregnancy if the initial embryo transfer has been successful. This process makes a new embryo transfer possible in a simple way without the need for further hormonal stimulation. It also allows the conservation of embryos in the case of a ‘fresh’ embryo transfer unexpectedly not being possible.
Vitrification is the method of cryopreservation most widely used in assisted reproduction, particularly in the cases of oocytes and embryos. The freezing process is very fast in order to prevent the formation of ice crystals that could damage the cells, and cellular survival and viability rates are very high.Thanks to this technique embryo transfer results for thawed embryos have improved considerably over recent years.
Not all of the embryos obtained are suitable for cryopreservation. Cryopreservation is only used when embryo quality is sufficiently high.
How are cryopreserved embryos thawed and transferred?
When previously frozen embryos have to be transferred, the patient will need to take medication in order to prepare the uterus; usually oral or transdermal hormonal treatments. Between the twelfth and the fourteenth day of the cycle an ultrasound scan is performed in order to determine the thickness of the endometrium (the inner layer of the uterus) and then the appropriate time for the transfer is set. This procedure can also be carried out without medication, controlling the woman’s natural cycle and performing the embryo transfer at the best time.
Prior to transfer, the embryos must be thawed and assessed, although embryo viability is good — it is calculated that around 90% of thawed embryos can be transferred in good condition.
This is the inverse of the freezing process in the sense that the embryo now needs to be correctly rehydrated. Once this has been achieved, it is kept in a culture medium until it is time for it to be transferred. The transfer process will be identical to the one previously described for the transfer of ‘fresh’ embryos.
How can an IVF treatment be organised if I don’t live in Barcelona?
Not living in Barcelona is not a problem at all. An initial appointment at our centre is essential, so that we can assess your full medical history, and advise on the correct treatment for you. Once the treatment is started, medical check ups can take place outside Barcelona, as long as they are carried out by an experienced gynaecologist. Our medical team will assess the information received, and will adjust medication as necessary throughout. Follicular aspiration and embryo transfer will take place at our centre at an agreed day and time.