ICSI is a kind of assisted microsurgical fertilization that entails the injection of a single sperm immediately into an egg. Over the last few years, various techniques of assisted microsurgical fertilization (micromanipulation procedures) have been developed for use when the male partner exhibits severe oligoasthenospermia or asthenospermia (poor motility and/or low sperm count). ICSI permits a much higher fertilization rate for these patients with “normal” fertilization in over 50% of the eggs.
Eggs for ICSI are taken in precisely the same way as those for IVF. After egg retrieval, the cells surrounding each egg are delicately removed. The eggs are then checked under a microscope, and only those who have extruded the first polar body (a structure indicating egg maturity) are suitable for injection. Typically, 70% of the eggs that are collected are suitable for ICSI.
The sperms are washed and prepped. Theoretically, the minimum number of sperms needed is equal to the number of eggs to be injected. The egg and the sperm are then placed on a special microscope, which has micromanipulators attached to it. One micromanipulator keeps the egg in place, while the other is used to insert the sperm into the egg. The remainder of the procedure is similar to the standard in vitro fertilization concerning the incubation of the eggs and the transfer of the resulting embryos. The ZIFT procedure may also be used to place the embryos directly into the fallopian tube. The remaining embryos can be frozen for future use.
This technique was pioneered by a group of physicians in Belgium. As of April 1994, the group reported the live birth of 289 children through this technique. They have noted seven major malformations or birth defects. The percentage of major birth defects (7 out of 289 or 2.4%) falls within the range of malformations in the general population.