Fluorescent In Situ Hybridization (FISH) technique is a molecular cytogenetic method based on the hybridization of normal DNA fragments (probes) labeled with fluorescent dyes and the patient’s DNA in its environment without disturbing the chromosome structure. The FISH method can be used to detect numerical or structural anomalies of chromosomes before and after birth, as well as in cancer genetics and Preimplantation Genetic Diagnosis (PGD). The test result can be obtained in 5-7 days.