Unlike insemination, this technique consists of obtaining the ova, fertilising them in the laboratory and then placing them in the uterus. This technique is the most similar to the pregnancy process and is the one that offers the highest success rate per attempt. It comprises the following steps:

 

1. Ovarian stimulation:

Drugs are usually used to stimulate a greater production of ova (between 10 and 12 ova, i.e. superovulation) to increase the possibility of success. This stage is controlled using vaginal echographs and tests to determine the level of blood estradiol. When the follicles are thought to be mature (a diameter of between 16-18 mm), the extraction of the ova is programmed. If an excessive number of follicles are observed on the echograph, it may be appropriate to cancel the stimulation due to the risk of developing what is known as ovarian hyperstimulation syndrome, characterised by an accumulation of liquid in the abdomen, abdominal pain or discomfort, a considerable increase in the size of the ovaries and haemoconcentration, etc., which may ultimately require hospital treatment.

 

2. Obtaining the ova:

Once the follicles have matured, the ova are sucked from them. This is carried out via echograph-controlled ovarian puncture in the operating theatre under mild sedation. The operation usually takes around 15 minutes and the patient usually goes home two hours later as normal. The follicular liquid is sent to the laboratory where the ova are located under a microscope and their quality and maturity are assessed.

 

3. The fertilisation of the ova and the embryonic culture:

The ovum-spermatozoon are brought together on the same day as the extraction, which means that a sample of semen must be provided by the man. Depending on the causes of the sterility, the same number of ova as spermatozoons can be placed on a Petri dish or an intra-cytoplasmic sperm injection (ICSI) is performed, which consists of inserting a spermatozoon into each ovum under a microscope. This technique, which practically guarantees the union between the ovum and the spermatozoon, an essential step in achieving the pregnancy, is used in almost all IVF treatments.

After 16 hours, the ova are examined under a microscope to find out how many of them have been fertilised. After a few more hours in culture, the fertilised ova begin to separate, marking the beginning of the embryo development. Once they have separated, their morphology is assessed to discover the number of viable embryos and specify the day for the embryo transfer.

 

4. Embryo transfer:

Unlike the extraction, the process for returning the embryos to the uterus does not require anaesthetics and is usually a fast and simple procedure. Once the number of viable embryos is known, a decision is taken as to how many will be transferred and the rest are cryo-preserved and stored in the embryo bank for subsequent attempts. The number of embryos to be transferred is determined on the basis of various parameters such as embryo quality, characteristics and age of the patient, previous pregnancy attempts via IVF, etc., but usually, no more than two are transferred. The pregnancy test is performed after 12-14 days.