A possible, if somewhat rarer, reason for infertility is a high number of chromosome maldistributions in the sperm. This can limit the probability of fertilisation and increase the risk of miscarriage or a chromosomal disorder. Some of these configurations can even give an indication for pre-implantation diagnosis (PGD).
To make things clear: with FISH semen analysis, we can assess the chances of success of IVF or ICSI therapy.
But how do we recognise chromosome maldistributions? FISH semen analysis (fluorescent in situ hybridisation) works by adding special ‘tracers’ - coloured nucleic acids. These then bind to the chromosomes to be looked at, and appear fluorescent under the microscope.
In men with normal sperm quality, the average number of maldistributions in the sperm is five to seven percent. However, men with a significantly reduced sperm count or a high proportion of malformed sperm can show values of 30% or more, and thus an additional reduction in fertility. The FISH test is therefore recommended in cases of significantly limited sperm quality, but also before a scheduled polar body diagnosis. With low sperm concentrations, successful analysis may also be possible by pooling several semen samples.