In this procedure, after egg retrieval, the cells surrounding the eggs are removed to assess the maturity of the egg. Then with the help of a high magnification microscope, the embryologist selects a single, good quality, normal looking sperm and injects it with help of a very fine glass needle into a mature egg in order to achieve fertilization. This process is repeated for each and every mature egg that has been retrieved.

Once the process of sperm injection has been completed, the eggs are kept back in the incubator to ‘fertilize’ overnight.  Despite injecting sperm inside each egg, not all eggs will fertilize. On an average, about 60-70% of eggs that are injected will fertilize. Once an egg fertilizes, it produces a zygote the next day. 

ICSI is also a treatment option for men who have azoospermia i.e no sperm in their semen. For such men, we can retrieve sperm directly from the testis either with the help of a simple fine needle biopsy known as TESA or PESA, or sperm may have to be surgically extracted with the help of a procedure known as TESE. These techniques coupled with IVF-ICSI offer a chance to men with no sperm in their semen to have a child with their own sperm.