Fluorescence in situ hybridization (FISH) in Human Sperm

It has been reported that 12% of the population has fertility problems. The male factor in infertility is proving to make up about 50% of all couples consulting Assisted Reproduction clinics.

The semen analysis is the first test performed to evaluate male fertility and it consists of measuring sperm concentration, motility, morphology, and the presence of other cells. We find out a lot of information about the male genital tract by the volume, liquefaction time and the pH and the other parameters tell us about sperm quantity and quality. Many times this routine semen analysis indicates that further studies ought to be carried out.

The causes of male factor infertility are multifactorial with an estimated 50% due to or contributed by genetic abnormalities. In men, these errors in sperm can lead to the embryo not prospering, not implanting or the pregnancy ending in a miscarriage. There is also an increased risk of transmitting abnormalities to the offspring.

It has been stated that genetic problems are more prevalent in sperm from men with abnormal semen analysis. Even though the sperm is within normal parameters, this does not guarantee a normal genetic situation. Many times looking for reasons why IVF cycles have failed the doctor will want the sperm to be further tested and FISH testing is a possibility.

Fluorescence in situ hybridization (FISH) in sperm is a technique used to analyze chromosomal abnormalities in male gametes. FISH detects aneuploidies i.e. the presence of an abnormal number of chromosomes in a cell.

Surprisingly, even in the best of circumstances it is calculated that al least 10% of sperm is not chromosomally normal. When FISH is performed and the test is abnormal, decisions must be made. The couple can continue using the sperm and hope for the best, they can change to donor sperm (which is a very difficult decision to have to face) and another good option is to offer the couple is Preimplatation Genetic Diagnosis. The information that we obtain from embryo biopsy can tell us in over 98% of the time if the embryo is normal or it is affected.

Preimplantation Genetic Diagnosis gives couples great hope in having a healthy baby and also helps in the decision on whether or not it is imperative to use donor sperm if all embryos biopsied are abnormal.

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