The application of molecular genetic tests like fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) has been extended to detect embryos with major sporadic chromosomal or age-related aneuploidies that may result in failure of implantation or spontaneous miscarriage and to remove them from the cohort available for transfer. This technique is called preimplantation genetic screening (PGS) according to the European Society of Human Reproduction and Embryology (ESHRE) and the European Society of Human Genetics (ESHG). PGS was renamed Preimplantation genetic Testing for aneuploidy (PGT-A) and PGD was renamed by Preimplantation Genetic Testing for Monogenic/Single-Gene Disorders (PGT-M) by Preimplantation Genetic Diagnosis International Society (PGDIS) in 2016 The technology used by both PGD and PGS is nearly identical. PGT- A aims to improve pregnancy rates in sub-fertile couples undergoing IVF/ICSI treatment. PGT-M aims to prevent the birth of affected children in fertile couples with a high risk of transmitting genetic disorders. PGS or aneuploidy screening is important as 50% of cleavage embryos are abnormal, 80% of embryos in women > 42yrs of age. Most aneuploidy embryos arrest before cavitation and prior to blast development. Aneuploidy causes 60% sporadic miscarriages, 40% recurrent miscarriages.

Preimplantation Genetic Testing for Monogenic/Single-Gene Disorders (PGT-M) of single gene disorder by DNA amplification-depends on DNA amplification using PCR -has pitfalls as allele drop outs, contamination reduced amplification efficiency.