It is called fertilization failure when the process of in vitro fertilization , either conventional or ICSI, fails and does not fertilize any egg. This is a phenomenon that usually occurs in 11-15% of treatments with fertilization in vitro and 3% after the use of ICSI.
After the follicular puncture, where the eggs are retrieved, this is fertilized in the laboratory:
- If we speak of fertilization by means of conventional IVF, the egg will be incubated with a sufficiently high concentration of spermatozoa so that fertilization occurs spontaneously. The egg and sperm will be incubated for several hours and the next day the laboratory team will check that these eggs have been fertilized.
- In a treatment with IVF-ICSI, after the follicular puncture a sperm will be injected into the egg. In this way the male cell is forced into the egg. However, this invasion does not guarantee that the egg and sperm will create an embryo. This process can be disrupted, leading to failure of fertilization.
Faced with this phenomenon, or a case of low fertilization, it is necessary to rethink the patient's cycle and look for the origin of this failure if possible. If the failure of fertilization has taken place after a conventional IVF and an unknown origin of sterility, it is recommended to perform ICSI in consecutive cycles.
Fertilization failure after ICSI is usually due to poor oocyte quality or poor sperm quality.