Implementation and Different Aspects of Preimplantation Genetic Screening (PGS): A Narrative Review

Abstract

Aneuploidy is considered to be the most common chromosomal disorder and is the most common disorder during IVF treatment. In patients with recurrent abortion that present normal karyotype, preimplantation genetic screening (PGS) has been advised for exploring the presence of aneuploidy which decline abortion rate and result to a higher rate of a healthy pregnancy and live birth. There are various debatable indications for preimplantation genetic screening; the first indication of PGS is maternal age. The genetic material biopsy steps for performing PGS is one of these three techniques; biopsy of the polar body, blastomere in the cleavage stage, and trophectoderm in the blastocyst stage. Three types of protocols are used for controlled ovarian stimulation: the long-term GnRH agonist, the GnRH antagonist protocol, and the microsimulation protocol . There are various techniques for genetic screening, the most recent one is the "fluorescence in situ hybridization (FISH)" technique for aneuploidy screening; other techniques include "comparative genomic hybridization (aCGH), “single nucleotide polymorphism (SNP)”, “quantitative polymerase chain reaction (qPCR)", and “next-generation sequencing technology (NGS)”. The aim of this study is to investigate the implementation of PGS and different aspects of this technique to improve pregnancy outcomes. With the possibility of access to assisted reproductive technology and the possibility of oocyte screening and selection of normal oocytes, it is believed that the birth rate of a normal child in couples will increase. Infertility treatment is a costly process and many couples are affected by that. But its beneficial information can help make clinical decisions, and it can be recommended to couples if it improves the outcome of pregnancy, increases the number of live births, and reduces pregnancy loss.