Using the FISH (Fluorescence in situ Hybridisation) technique, we can analyse the chromosomes in the sperm. Human cells have 46 chromosomes, but sperm and eggs have 23 each. When a sperm has 22 or 24, the resulting embryo will also have one more or less, which can lead to miscarriage or failure to implant. This test is therefore recommended if a couple report these problems, or if the male has a very low sperm count.
If a patient has a higher percentage of sperm with alterations to the chromosome count, it is necessary to study the resulting embryos to identify the normal chromosomes. This is done by carrying out a cycle of in vitro fertilisation with pre-implantation genetic diagnosis (PGD).