High fertilization and implantation rates after intracytoplasmic sperm injection

Previously reported better fertilization rate after intra-cytoplasmicsingle sperm injection (ICSI) than after subzonal inseminationof several spermatozoa was confirmed in a controlled comparisonof the two procedures in 11 patients. Intracytoplasmic sperminjection was carried out in 150 consecutive treatment cyclesof 150 infertile couples, who had failed to have fertilizedoocytes after standard in-vitro fertilization (IVF) proceduresor who were not accepted for IVF because not enough motile spermatozoawere present in the ejaculate. A single spermatozoon was injectedinto the ooplasm of 1409 metaphase II oocytes. Only 117 oocytes(8.3%) were damaged by the procedure and 830 oocytes (64.2%of the successfully injected oocytes) had two distinct pronucleithe morning after the injection procedure. The fertilizationrate was not influenced by semen characteristics. After 24 hof further in-vitro culture, 71.2% of these oocytes developedinto embryos, which were transferred or cryopreserved. Only15 patients did not have embryos replaced. Three-quarters ofthe transfers were triple-embryo transfers. High pregnancy rateswere noticed since 67 pregnancies were achieved, of which 53were clinical, i.e. a total and clinical pregnancy rate of 44.7%and 35.3% per started cycle and 49.6% and 39.2% per embryo transfer.A total of 237 supernumerary embryos were cryopreserved in 71treatment cycles.