You have learned that the result of your prenatal genetic screen is "screen positive".
This result does not mean your baby has Down syndrome, trisomy 18 or an open neural tube defect. In fact, most women with this result do not have a baby with one of these conditions. The result means that the chance of your baby having Down syndrome, trisomy 18 or an open neural tube defect is high enough that diagnostic testing is offered. Diagnostic testing tells you for sure if your baby has any of these three conditions.
As part of your screen result, you have been given a number that estimates the chance your baby has one of these conditions.
Here is an example of a screen positive result:
The chance of Down syndrome is 1:100. This is the same as saying:
• There is a 1% chance your baby will have Down syndrome, or
• There is a 99% chance your baby will not have Down syndrome, or
• If 100 women had the same result, one of them would have a baby with Down syndrome and the other 99 would not.
What happens now?
Your health care provider may need to confirm how far along you are in your pregnancy. It is important to make sure the pregnancy dating used for the prenatal screen result is correct.
If you have a screen positive result for an open neural tube defect, you will be offered a detailed ultrasound and an appointment with a maternal fetal medicine doctor or a genetic counsellor at one of BC's medical genetics clinics in Vancouver or Victoria. If your baby has an open neural tube defect, this is usually seen on the ultrasound scan.
If you have a screen positive result for Down syndrome or trisomy 18, you will be offered an amniocentesis to find out for sure if the baby has one of these conditions. Amniocentesis has a 1 in 200 chance of pregnancy loss.
My prenatal screen result is screen positive for Down syndrome or trisomy 18? Should I have an amniocentesis?
It is your choice. Think about these questions to help make up your mind.
- Do I think the chance that is given on my screen result is high or low?
- Do I need to know for sure if my baby has Down syndrome or trisomy 18 before the baby is born?
- If I find out that my baby has Down syndrome or trisomy 18, what will I do with this information? Will I end the pregnancy? Will I continue the pregnancy? Will I use the information to prepare for a child with special needs? Will I put the baby up for adoption?
- Most women who have the amniocentesis do not lose their pregnancy, but do I think the 1 in 200 chance of pregnancy loss is too high for me to take?
- Will I feel too worried for the rest of my pregnancy if I do not have the amniocentesis?
- What would be more difficult for me? If I have the amniocentesis and lose the pregnancy, or if I don't have the amniocentesis and find out when my baby is born that the baby has Down syndrome or trisomy 18?
What if I am having trouble deciding whether having an amniocentesis is right for me?
After speaking with your health care provider if you are still undecided regarding amniocentesis you can be referred for genetic counselling to a maternal fetal medicine specialist or to medical genetics in either Vancouver or Victoria. Both medical genetics programs offer face-to-face and telehealth counselling. Telephone counselling could be done if telehealth is not available. The decision to refer for genetic counselling should be a joint decision between you and your health care provider.
What if the result of the amniocentesis or detailed ultrasound shows that the baby has one of these conditions?
Your health care provider, as well as medical geneticists and genetic counsellors, are available to discuss your choices with you and to help you make a decision that is right for you.
You can also download the pamphlet "A Screen Positive Result: What does it mean and what do I do now? ".
