Is there hope for me following fertilisation failure after ICSI?

In vitro fertilisation treatment (IVF) techniques consist of fertilising oocytes with spermatozoa in a laboratory. They are held under conditions that are similar to their natural environment and, a few days later, the best embryo is selected and placed in the woman’s uterus where it remains until it implants. From this point on, monitoring procedures are the same as in any other spontaneous or natural pregnancy.

The first, essential step, therefore, is to get the spermatozoon to fertilise the oocyte. Conventional IVF consists of bringing oocytes and spermatozoa together and leaving the spermatozoa to fertilise the oocyte by themselves. As such, it is the most physiological of all the techniques and the one that involves the least amount of intervention or handling. However, there are cases in which certain abnormalities in the oocytes or the spermatozoa stop fertilisation from taking place. In the 1990s, the intracytoplasmic spermatozoa injection (ICSI) technique was developed. It can be defined as the introduction of a spermatozoon into a mature oocyte in order to achieve fertilisation. This technique provides a solution for many male fertility issues, as well as for certain issues with oocytes.

Despite the huge progress that the option of ICSI provided, there are currently between 1 and 3% fertilisation failures following use of this procedure. Fortunately, the number of cases is low but it is essential that the couples who do experience a failure are given an explanation. We know that the main cause of these failures is an abnormality in the oocyte activation process. The process consists of a number of changes that are initiated by the spermatozoon when it enters the oocyte and that end when it is fertilised. If the spermatozoon is unable to initiate the changes or if the oocyte is unable to generate them, fertilisation will not take place.

Assisted oocyte activation techniques have been developed and these involve ‘giving a helping hand’ so that the fertilisation process can begin. The main means of doing so involve using electrical or chemical stimuli. Whilst their use has expanded as part of IVF laboratory techniques, they are still not permitted in many countries. Recent research demonstrates that these techniques have made it possible to achieve normal fertilisation levels in some patients. These promising studies indicate that it is a safe technique but that additional research is needed in order to confirm this fact.

We are increasingly close to finding new solutions that will shortly enable these couples to make their dream of being parents come true.

María Carmen Tió, biologist at Instituto Bernabeu