INTRACYTOPLASMIC SPERM INJECTION (ICSI)

The use of ICSI provides an effective treatment for male factor infertility. The negative effects of abnormal semen characteristics and sperm quality on fertilization can be overcome with ICSI if viable sperm are available because the technique penetrates the shell (zona pellucida) around the egg and the egg membrane (oolemma) to deliver the sperm directly into the egg. ICSI involves the direct injection of a single sperm into the interior of an egg using an extremely thin glass needle. ICSI allows couples with severe male factor infertility to achieve fertilization and live birth rates similar to those achieved with in vitro fertilization (IVF) using conventional methods of fertilization in men with normal sperm counts. ICSI can be performed even in men with no sperm in the ejaculate if sperm can be successfully collected from the epididymis or the testis.
ICSI has been reported to be associated with a slightly higher risk of birth defects in some studies. However, it was unclear in those studies whether the association is due to the ICSI procedure per se or to inherent defects in the sperm from men who have severely abnormal sperm, thus requiring ICSI. The risk of birth defects after ICSI is quite small. (4.2% versus ~3% of those conceived naturally). Experts are still debating the impact of ICSI on the intellectual and motor development of children. Most recent studies have not detected any differences in the development or the abilities of children born after ICSI, conventional IVF, or natural conception.
The prevalence of sex chromosome abnormalities in children conceived via ICSI is higher than observed in the general IVF population, but the absolute difference between the two groups is small (0.8% to 1.0% in ICSI offspring vs. 0.2% in the general IVF population). The reason for the increased prevalence of chromosomal anomalies observed in ICSI offspring is not clear. It may be caused by the ICSI procedure itself, or the father. Men with sperm problems (low count, poor motility, and/or abnormal shape) are more likely themselves to have genetic abnormalities and often produce sperm with abnormal chromosomes; the sex chromosomes (X and Y) in the sperm of men with abnormal semen parameters appear especially prone to abnormalities. If sperm with abnormal chromosomes produce pregnancies, these pregnancies will likely carry these same defects. Translocations (a re-arrangement of chromosomes that can cause birth defects, or miscarriage) may be more common after ICSI.
Some men are infertile because the tubes connecting the testes to the penis did not form correctly. This condition, called congenital bilateral absence of the vas deferens (CBAVD), can be bypassed by aspirating sperm directly from the testicles or epididymis and using them in IVF with ICSI to achieve fertilization. However, men with CBAVD are affected with a mild form of cystic fibrosis (CF), and this gene will be passed on to their offspring. All men with CVABD, as well as their partners, should be tested for CF gene mutations prior to treatment, so that the risk of their offspring having CF can be estimated and appropriate testing performed. It is important
to understand that there may be CF gene mutations that are not detectable by current testing and parents who test negative for CF mutations can still have children affected with CF.
Some men with extremely low sperm counts or no sperm may have abnormalities (microdeletions) in their Y chromosomes. Testicular biopsy and successful retrieval of viable sperm can be used to fertilize eggs with ICSI. However, any sperm containing a Y chromosome microdeletion will be transmitted to the male child. Thus the risk that male offspring might later manifest disorders including infertility is very real. However, men without a detectable deletion by blood testing can generate offspring having a Y chromosome microdeletion, because the chromosomes in the sperm may not be the same as those seen when tested by a blood test.
Rescue ICSI: In some cases, unexpectedly none of the eggs fertilize by regular insemination. When this lack of fertilization is discovered the next day, an attempt may be made to inseminate some of these unfertilized eggs with ICSI. Embryos resulting from rescue ICSI appear to have reduced potential for pregnancy and may have increased risk of genetic abnormalities.