This is a sperm-preparation technique designed to select sperm that are not damaged or programmed to die (apoptic sperm cells) so that this sperm can be used in assisted reproductive techniques, thus increasing potential for fertilization. MACS makes it possible to immunomagnetically select sperm that has intact DNA. Healthy sperm is separated from sperm that is dead or has fragmented DNA. It is recommended when  it is suspected that DNA fragmentation in sperm is substantially linked to poor outcomes reached with prior assisted reproductive techniques.