Cystic Fibrosis: Prenatal Screening & Diagnosis
What is cystic fibrosis?
Cystic Fibrosis (CF) is a genetically inherited disorder affecting children and young adults. This disorder leads to problems with digestion and respiration, and can shorten the life-span of an individual. Symptoms of CF include build-up of thick mucus in the lungs causing congestion and associated respiratory problems. Mucus build up is also seen in the digestive tract leading to difficulty in the absorption of nutrients.
What are the tests for prenatal screening and diagnosis of cystic fibrosis?
Prenatal screening tests are safe procedures used to determine if an expectant mother is likely to have a baby with a birth defect. Pre-natal tests to detect CF include chorionic villus sampling (CVS) and amniocentesis.
- Chorionic villus sampling (CVS): Prenatal test done in weeks 10 and 12 of pregnancy in which a sample of chorionic villus - wispy projections in the placenta (structure that develops in the uterus during pregnancy to provide oxygen and nutrients to the growing baby) is removed and tested to confirm or rule out CF in the baby.
- Amniocentesis: Prenatal procedure in which a sample of amniotic fluid (fluid that surrounds and protects a baby in the uterus) is removed and tested to check if the baby has CF.
What are the associated risks?
Certain risks are common to both the prenatal tests. They include miscarriage, Rh sensitization (occurs in women with Rh negative blood), and uterine infection. Amniocentesis carries additional risks, although rare, such as needle injury, which may occur if the baby moves in the path of the needle used during the procedure. Also, the baby might develop orthopaedic problems if there is chronic leakage of the amniotic fluid after the procedure.
Preconception Carrier Screening
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 foetus (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.
What is Carrier Screening?
An important step in such tests is 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 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
What are the benefits of pre-conception carrier screening?
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.