Intracytoplasmic sperm injection: a powerful tool to overcome fertilization failure.

OBJECTIVE

To describe the novel micromanipulation technique known as intracytoplasmic sperm injection (ICSI), which has been applied successfully to treat male factor infertility, even in patients with severely impaired sperm characteristics. This paper reviews the historical aspects that led to the development of ICSI in the animal model as well as the current experience in the human.

DESIGN

Before using assisted fertilization techniques to enhance fertilization of human gametes, it is imperative that practitioners gain extensive experience in the animal model. In addition, criteria for accepting individuals for treatment with ICSI are discussed along with other applications of the procedure in infertile couples who do not benefit from standard IVF.

RESULTS

Because ICSI resulted in limited success in animal models, it seemed unlikely that it would be successful in humans. Yet, ICSI now appears to be the most successful and significant innovation developed for dealing with male factor infertility since the emergence of IVF itself. To date, a relatively large group of healthy children have been born from this technology and there appears to be no increased incidence of congenital malformations.

CONCLUSIONS

The consistently high success rate resulting from the application of ICSI to treat couples with male factor infertility is comparable to the results obtained using standard IVF techniques performed in nonmale factor couples. This finding indicates that spermatozoa obtained from subfertile men selected for intracytoplasmic injection are usually genotypically normal.