Carrier Screening before Family Planning
Preconception Carrier Screening is a screening option, available for a woman planning to become pregnant, that allows her doctor to identify conditions which have the potential to adversely impact the health of her fetus (developing baby) in the future. This is done at a point in time when the woman can have the widest range of personal and reproductive choices and helps to predict the possibility of having a child with a genetic disorder.
An important step in such tests is an identification of a carrier (a person with either mild or no symptoms of the disorder, but capable of passing on the disorder to his or her child through a particular gene). This involves genetic counselling and laboratory testing of blood or saliva. In genetic counselling, a genetic counsellor goes through your family medical history, which helps him to determine if your baby is likely to have a genetic disorder based on the following:
- A history of genetic disorders runs in your family
- You have a genetic disorder
- You already have a child with a genetic disorder
- Your race or ethnicity
A preconception carrier test lets you know whether you and/or your partner are carriers of a disease, and helps you to make important pregnancy-related decisions. If you are a carrier, you may decide to get pregnant with the option of considering prenatal diagnosis (diagnosis of abnormalities), use In vitro fertilization or even choose not to become pregnant.
Preimplantation Genetic Screening (PGS)
Assisted reproductive technology (ART) is a field of medicine for the treatment of infertility. ART assists in the fertilization of the sperm and egg (outside a woman’s body, in a lab), either through in vitro fertilization (IVF) or intra-cytoplasmic sperm injection (ICSI). Preimplantation genetic screening (PGS) is a diagnostic tool used to examine embryos formed through these methods, for chromosomal abnormalities, which is the chief cause of miscarriage and embryo implantation failure in the womb. The process is also called aneuploidy screening as it identifies aneuploidy abnormalities, which refers to the presence of an abnormal number of chromosomes.
PGS is recommended for women over 35 years of age with repeated implantation failures, recurrent pregnancy losses, family history of chromosomal problems and partners with male factor infertility.
Procedure of PGS
Your doctor first performs normal IVF procedures, which involves the collection of mature eggs from the ovaries and fertilization with sperm in the lab. The resulting embryos are cultured in the laboratory for two to three days or five to six days, until the embryo has several actively dividing cells. A few cells are removed at this stage and tested for chromosomal abnormalities. The healthy embryos are then transferred into the womb for development, while those with an abnormal number of chromosomes are destroyed.
As with any procedure, PGS may involve certain risks and complications such as the probability of having no embryos left for transfer after the screening or the damage of some during the cell removal process. It is important to remember that PGS screening does not guarantee against miscarriages.