The conventional IVF is considered as the least invasive technique to naturally fertilize an egg. Following the collection process, the eggs and the sperm are stored together under special conditions, similar to those in the body of a woman, so that the most suitable sperm is able to fertilize the egg within a few hours.
This procedure is characterised as the least invasive, since the most “capable – healthy” sperm is the one that will fertilize the egg and not another accidental sperm, which may not be ideal for fertilization purposes.
In other words, the ovum is capable of screening and selecting the fittest sperm, a fact that will secure its subsequent development into a foetus.
However, the conventional IVF depends on the quality of the sperm. What is evaluated is the motility, the number and the morphology of spermatozoa. If any of these parameters is affected, then one will ultimately need to resort to microinjection (ICSI).