This method is employed when the spermatozoa are normal in concentration, motility and morphology. Approximately 1 million sperm cells (adjusted by their final concentration after wash) per egg are dispersed in a drop of insemination medium and incubated at 37 o C with 5-6% CO2, until the next day. The sperm cells are left to penetrate the outer membrane of the egg, on their own, to fertilize the egg. Fertilization is determined 17-19 hours after insemination.
The method of ICSI (intracytoplasmic sperm injection) is mainly used when the semen analysis is abnormal, i.e. when the sperm count is low, when there is low motility or severe morphological defects. This method is also applied in cases of continuous failed fertilization with classical IVF, in the presence of sperm antibodies and occasionally in patients with a small number of retrieved oocytes. It is also applied in cases of idiopathic infertility. Briefly, the embryologist is manually selecting the normal looking spermatozoa and injects the eggs with the use of Special equipment and micro tools. Fertilization is determined 16-18 hours after injection.