What are chromosome abnormalities?
Chromosomes are the structures which carry genes. If genes are the words of a book which the genetic code reads to make a baby develop, then chromosomes could be thought of as chapters. There are always two copies of the chromosomes, or two of the same chapter. Sometimes, and more often with increasing maternal age, chapters in the book can triple [also known as Trisomy] instead of double, and this can lead to syndromes such as Trisomy 13, Trisomy 18 [Edward’s Syndrome] and Trisomy 21 [Down Syndrome].
Who will do the test?
Dr. Seethram is a practising obstetrician, who has been doing ultrasound for 14 years. He obtained his clinical training for FTS at Mt. Sinai Hospital in Toronto, under the supervision of the FTS director, Dr. Nan Okun. He is certified and licensed by Fetal Medicine Foundation UK (www.fetalmedicine.com) for NT, NB, DV diagnosis. FMK requires regular image and data audits as part of the quality assurance program. Dr. Seethram is widely regarded as an expert in the field of early pregnancy screening, and gives numerous talks on the subject.
How is the first trimester screening test done?
An obstetrician trained and certified in first trimester ultrasound for genetics conducts the first trimester screening test. A few measurements are taken, including a neck thickness and nasal bone measurement, then combined with the blood tests to provide a risk estimate.
What does a ‘Screen Positive’ result mean?
It means that your baby’s chance of having Trisomy is higher than usual. Approximately 3-5% of women receive a Screen Positive result. It’s important to note that a Screen Positive does not mean your baby will definitely have Trisomy; it only indicates an increased risk. The vast majority of ‘Screen Positive’ pregnancies result in babies that do NOT have a Trisomy syndrome.
What happens if the result is Screen Positive?
Our genetic counselor will review all results with you at the time of the screen, and discuss and/or arrange invasive testing options if required.
What does a ‘Screen Negative’ result mean?
It means that the results are in the normal range and no further testing is required.
Approximately 95-97% of women have Screen Negative results. In a very small number of women, the negative result can still miss a baby with Down’s Syndrome.
What is involved in a screening test?
A few things: an early ultrasound; blood work; and extensive counseling to assist you in understanding the test. When the test is completed, you will walk away with knowledge, understanding, and a more detailed acceptance of pregnancy risk. You will also have the opportunity to arrange further testing if required. The goal of the test is to provide you with more information, so that an informed decision can be made regarding further pregnancy testing.
If I have a first trimester screening test, can I skip the other tests later in pregnancy?
No. First trimester screening largely looks only at first trimester Trisomy risk. However, the test can also pick up problems with the placenta, which may require monitoring later in pregnancy. As well, second trimester blood work for spinal cord defect screening is advised [known as MSAFP] unless a 18-22 week ultrasound is going to be done. Your own health provider will counsel you regarding the value of later pregnancy ultrasound and other genetic tests offered later in pregnancy.
How does it compare to conventional screening?
Currently, the only other options available are maternal serum screening done at 16 weeks of pregnancy, detailed ultrasound evaluation done at 18 to 22 weeks, and invasive testing such as amniocentesis and chorionic villus sampling. Of all the non-invasive tests, no single test is superior to the first trimester screen in detection rates.
What are the benefits of early pregnancy screening?
- Help to detect Down Syndrome, Edward’s and Patau’s syndromes
- Confirm due dates
- Ensure a healthy fetus
- Assist in early pregnancy bonding (for the expectant mother and family)
- Examine placental and fetal anatomy
Can FTS determine the gender of my baby?
Fetal gender determination is possible on ultrasound. However, the College of Physicians and Surgeons of British Columbia mandates that ultrasound not be conducted for the purpose of gender determination. ; As well, the sex of the baby is more accurately determined in the second trimester.
If my test is abnormal, who will make the appropriate arrangements for follow up testing?
Your health care provider in pregnancy will be sent the reports of FTS immediately after their completion. When you meet with our genetic counselor, she will organize the necessary invasive testing, if that is what you decide on. We coordinate this testing with BC Women’s Hospital, and your primary care provider.