by Dr Agilan Arjunan, Fertility Specialist & Gynaecologist , KL Fertility Centre ( Malaysia)
The science involved in the treatment of infertility has rapidly advanced in the past few years . This advancement is clearly seen in the field of In-Vitro Fertilisation or IVF.
Current technology enables us to look into the genetics of human reproduction. Genetic testing also provides answers to infertility; and in some cases solutions.
Preimplantation Genetic Screening ( PGS)
IVF involves creating embryos in an IVF laboratory and replacing the embryo/embryos back into the womb.
Traditionally an embryo is graded based on its morphology ( external appearance under a microscope). The embryo/embryos with the best gradings is/are transferred back into the womb.
A morphologically-normal embryo with the best grading does not necessarily indicate that the embryo is genetically normal ( euploid embryo).
A genetically-normal embryo will lead to a successful pregnancy , assuming there are no other factors contributing to a failed embryo implantation or pregnancy.
Preimplantation genetic diagnosis (PGS) looks at the genetic normality of the embryo prior to an embryo transfer procedure.
Embryos are typically grown up to 3 to 6 days before the biopsy is performed.
Biopsy of the embryos are done when the embryo is either 3 days old or when they have reached Day 5 or 6 , known as a blastocyst.
Biopsy of the blastocyst is usually preferred because more cells are obtained from the embryo thus increasing the chances of the PGS to be performed successfully.
To be able to perform the biopsy, a small opening is made on the outer layer of the embryo , using either mechanical, chemical or laser technology.