Intracytoplasmic sperm injection - ICSI

Abstract

For more than a decade in vitro fertilization (IVF) has been successful in the treatment of couples with long-standing infertility due to various aetiologies such as tubal disease, male-factor infertility, unexplained infertility and endometriosis. The usual fertilization rate in IVF for nonmale infertility cases is 60–70% of the inseminated cumulus-oocyte complexes and in andrological infertility it is only 20–30%. The lower the number of normally fertilized oocytes, the less chance there is of available embryos, so that patients may have no embryos to transfer. It has been the experience of all centres for reproductive medicine, including our own, that a certain number of couples with male-factor infertility cannot be helped by standard IVF treatment. After insemination with progressively motile spermatozoa the number of two-pronuclear oocytes was either zero or less than 5%. Furthermore, a sizeable number of couples cannot be accepted for IVF if the number of progressively motile spermatozoa in the ejaculate is below a certain threshold number such as 500 000. In the past five years, assisted fertilization procedures have been developed to circumvent the barriers that prevent sperm access to the ooplasma, namely the zona pellucida and the ooplasmic membrane. Pregnancies and births have been reported after partial zona dissection (PZD) and subzonal insemination (SUZI). The success rate of PZD and SUZI has remained moderate: the normal fertilization rate (two-pronuclear oocytes) has never exceeded 20–25% of the micromanipulated oocytes; only two-thirds of the patients have had embryo transfers of, usually, a low number of embryos, resulting in a reduced pregnancy and take-home baby rate.