Failed fertilization after clinical intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) has resulted in pregnancy and birth for many couples, including those with severe male factor infertility. However, even after ICSI, complete failure of fertilization occurs in 1-3% of cycles. Most cases occur due to low number of mature oocytes, failure of oocyte activation or non-availability of appropriate spermatozoa for injection. Given the significant emotional and financial involvement in assisted reproductive cycles, failure of fertilization in all mature oocytes is a distressful event. It is not predictable. Since follow-up ICSI cycles result in fertilization in 85% of cases, repeated ICSI attempts are suggested. Physicians should counsel patients experiencing repeated failure of fertilization after ICSI cycles about available options including donated oocytes/embryos, donor sperm insemination, adoption or remaining childless if these choices are not acceptable due to religious or ethical reasons. This review discusses the causes and remedies for failed fertilization after clinical ICSI.