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Causes of ICSI Problems

Jun 9, 2010 | By Carole Wegner

The technique of manually injecting a single egg with a single sperm is called intracytoplasmic sperm injection, or ICSI. ICSI has allowed men who were previously considered hopelessly infertile to conceive children. ICSI is performed to bypass various sperm problems including insufficient sperm number, abnormal swimming or no swimming ability, problems with binding to an egg and various defects in sperm shape. Problems with ICSI fall into two categories: technical problems and potential adverse outcomes to offspring created using ICSI.

Poor Technical Proficiency

ICSI is a technically demanding skill which requires months of practice with non-clinical materials or animal gametes before technical mastery is achieved. According to an article by Steven D. Fleming and Robert S. King published in the Cambridge University Press, the technician must be able to pick up a single sperm using a remote controlled needle, gently break the sperm membrane and inject the sperm into the egg without breaking the egg or introducing too much injection fluid, which can prevent fertilization.

Absence of Normal Sperm

In some cases, the sperm used to perform the ICSI is of such poor quality that it is difficult to find sufficient sperm that have a normal appearance. For instance, some sperm have multiple heads or grossly oversized heads that are too big to fit in the injection needle, according to Fleming and King. Other sperm have multiple tails or bent tails which are also abnormal. In some cases, a donor sperm sample is also prepared as backup to inject any eggs remaining after all the patient's normal sperm have been used.

Fragile Eggs

Some eggs have a defect that make them inherently fragile and unable to withstand the stresses of sperm injection. Egg membranes must be flexible enough to stretch as the needle pierces the egg membrane and then rebound to reseal the hole in the egg membrane when the needle is withdrawn. Dr Kevin S. Richter and colleagues reported in their July 2006 article in the "Journal of Experimental and Clinical Assisted Reproduction" that the use of lasers instead of glass needles to pierce the egg membrane did not significantly reduced breakage of fragile eggs.

Aids Inheritance of Abnormal Genes

Some causes of male infertility are due to genetic deletions on the Y chromosome which can be passed on to male offspring, according to the American Society for Reproductive Medicine. Men with congenital bilateral absence of the vas deferens called CBAVD need ICSI to reproduce because the normal route for sperm to exit the body, the vas deferens, is missing. Having CBAVD is highly associated with having the genetic abnormality that causes cystic fibrosis. Therefore men with CBAVD should be tested for cystic fibrosis before undergoing ICSI to prevent passing on this disease, according to the American Society for Reproductive Medicine.
Before ICSI, men with severe sperm defects could not conceive children. Because ICSI can bypass many sperm problems associated with infertility such as low count and swimming problems, men who were previously unable to have children through sexual intercourse can now pass on their genes, including those responsible for genetic diseases to their offspring.
Most studies have been reassuring about the effects of ICSI on offspring, showing no statistical increase in congenital defects in offspring conceived through ICSI compared to the general public, according to the practice committee of the American Society for Reproductive Medicine. However, the ASRM study also notes that the incidence of sex chromosomal abnormalities is increased in ICSI offspring, perhaps because defects in the Y chromosomes are commonly found in the population of men that use ICSI.

References

Article reviewed by David Fisher Last updated on: Jun 9, 2010

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