ICSI patients undergo the standard in vitro fertilization procedure with the exception that a single sperm cell is injected directly into each egg.

ICSI in these procedures, a single sperm is extracted directly from the male's reproductive tract, specially prepared, and inserted into the female's egg.

ICSI is a delicate embryological procedure that requires specialized tools (micromanipulation) and advanced training.

Research into intracytoplasmic sperm injection (ICSI) has focused on the impact of ICSI on the meiotic spindle. The spindle is a "web like" intracellular structure that is crucial for normal chromosome alignment and separation during fertilization.

Extensive research indicates that, overall there is no increase in the rate of birth defects, or other abnormalities, after the ICSI procedure. However, there is some concern that ICSI could increase the incidence of male infertility in offspring and that it could enhance the occurrence of rare sexual chromosomal abnormalities. In nature, the most viable sperm reaches and fertilizes the egg, however, in ICSI sperm are manually selected thus bypassing this natural selection process. Clinical data are not yet available to conclusively rule out this possibility.