There are several reasons:
- One of the distinctive features of oocyte donation is that if we don’t have enough mature oocytes, another donor can be assigned. In the case of conventional IVF, as the cells surrounding the oocytes do not have to be removed before their insemination, we cannot know whether these are mature or not. That is to say, the granulosa cells that surround the oocytes naturally, prevent us from seeing ifthe morphological characteristics thereof correspond to mature eggs. Thus, there is a risk of attributing lower quality oocytes and of not obtaining the desired number of embryos.
- With ICSI (intracytoplasmic sperm injection) we increase the percentage of fertilized oocytes and,therefore, the available embryos. It is a process whereby, after the removal of the granulosa cells surrounding the egg, the sperm is injected into the egg. That is, we know a priori how many eggs are mature and, in turn, we increase the chances of fertilization occurring by introducing sperm into the egg.
- ICSI allows us to use frozen semen with the same probability of success as with fresh semen, provided that the test thaw has turned out to be satisfactory. This test thaw will be done a few days after the first visit.