- The mature egg is held with a specialized holding pipette.
- A very delicate, sharp and hollow needle is used to immobilize and pick up a single sperm.
- This needle is then carefully inserted through the zona (shell of egg) and in to the cytoplasm of the egg.
- The sperm is injected in to the cytoplasm and the needle carefully removed.
- The eggs are checked the next morning for evidence of normal fertilization.
Most IVF programs see that about 70-85% of eggs injected using ICSI become fertilized. Pregnancy success rates for in vitro fertilization procedures with ICSI have been shown in some studies to be higher than for IVF without ICSI. This is because in many of the cases needing ICSI the female is relatively young and fertile (good egg quantity and quality) as compared to some of the women having IVF for reasons other than male factor infertility.
ICSI success rates vary according to the specifics of the individual case, the ICSI technique used, the skill of the individual performing the procedure, the overall quality of the laboratory, the quality of the eggs, and the embryo transfer skills of the infertility specialist physician performing the procedure.
Sometimes IVF with ICSI is done for "egg factor" cases - low ovarian reserve situations. This is when there is either a low number of eggs, or lower "quality" eggs (or often both). In such cases, ICSI fertilization and pregnancy success rates are somewhat lower (as a group) since the main determinant of IVF success is the quality of the transferred embryos - and the quality of the eggs is the most crucial factor determining the quality and viability of the resulting embryo.