When there is significant male infertility, the embryologist injects a sperm into each egg using a technique called ICSI. IMSI is a variation of ICSI using high magnification. ICSI can be useful for:

• Men with poor sperm morphology. Poor morphology makes sperm more susceptible to oxidation damage
• Men with a higher level of DNA fragmentation in their sperm. DNA fragmentation is a sign of oxidation damage
• People with few embryos developing to the blastocyst stage 
• People not pregnant despite the transfer of several reasonable quality embryos.