Over the past several years, various methods of assisted microsurgical fertilization or micromanipulation procedures have been developed for use when the male partner exhibits poor motility (asthenospermia) or abnormal count, motility, and shapes (oligoasthenoteratozoospermia). ICSI is a type of assisted microsurgical fertilization that involves the injection of a single sperm directly into an egg and improves the chances that fertilization will occur.
Eggs for ICSI are obtained in exactly the same way as those for IVF. Following egg retrieval, the cells surrounding each egg are carefully removed. The eggs are then examined under a microscope and only those that exhibit characteristics of maturity are suitable for injection. Typically, 70% of the eggs that are obtained are suitable.
Theoretically, with ICSI, a minimum number of sperm is needed: one sperm for each egg. Sperm is collected, washed, and prepared appropriately then placed, along with the egg, on a special microscope which has micromanipulators attached to it. One micromanipulator holds the egg in place while the other one is used to inject the sperm into the egg.
The remainder of the procedure is similar to standard in vitro fertilization: the eggs are incubated and transferred into the uterus when appropriate growth has been achieved. ZIFT may also be used to place the embryos directly into the fallopian tube and any excess embryos can be frozen for use in the future.
ICSI was pioneered by a group of physicians in Belgium. As of April 1994, this group reported 289 live births using this technique. Of these, 7 major malformations or birth defects were identified which falls within the range of malformations found in the general population. Recent information, however, indicates an increase in the incidence of major birth defects in pregnancies conceived using ICSI as compared with pregnancies conceived during natural occurring cycles (8.6% as compared to 4.2%). This may be the result of ART/IVF and not ICSI.