What factors affect intracytoplasmic sperm injection outcomes?

Within the last decade, intracytoplasmic sperm injection (ICSI), a new assisted reproductive technique that allows for the direct injection of spermatozoa into the oocyte, has become available to infertile couples. While most studies indicate that ICSI has success rates similar to those of traditional in vitro fertilization, there are many concerns about the safety of the procedure, including increased risks of chromosomal and developmental abnormalities in children conceived by ICSI. Factors that contribute to these increased risks have not been well elucidated. The purpose of this paper is to review the latest literature concerning 1) the adverse outcomes associated with ICSI; and 2) factors that affect the success rates of ICSI (with emphasis on paternal factors).