Positive Results
If your had a screening test (such as enhanced First Trimester Screening or Second Trimester Screening), and your results were "screen positive", you may have lots of questions about what your results mean and next steps.
What Does the Result Mean?
A "screen positive" result means there that there is a higher chance for the pregnancy to have trisomy 21 (Down syndrome) or trisomy 18. It does not mean that the pregnancy definitely has one of these chromosome differences.
Most of the time when there is a "screen positive" result, the pregnancy turns out to not have trisomy 21 or trisomy 18. This means that most of the time, the result is a false positive.
Why Is the Result "Screen Positive"?
"Screen Positive" for Trisomy 21
The test has a cut-off of 1 in 350 for trisomy 21. A "screen positive" result for trisomy 21 means that the chance that your pregnancy has this chromosome difference is higher than 1 in 350.
"Screen Positive" for Trisomy 18
The test has a cut-off of 1 in 200 for trisomy 18. A "screen positive" result for trisomy 18 means that the chance that your pregnancy has this chromosome difference is higher than 1 in 200.
Understanding Your Specific Chance
A "screen positive" report will tell you what your specific chance is that the pregnancy truly has trisomy 21 or trisomy 18.
You got a "screen positive" result for trisomy 21, and the number on your report is 1 in 100. You can think of it as a 1% chance that the baby has trisomy 21, and a 99% chance that the baby does not have trisomy 21.
Next Steps
If you have a "screen positive" result, you should be offered further testing options by your health-care provider.
As the next step, you can choose between one of the following three options:
| Non-Invasive Prenatal Testing (OHIP-funded) |
| Non-Invasive Prenatal Testing (NIPT) will now be funded by OHIP in your situation. NIPT is a more accurate screening test compared to the test you have already done. This test can be arranged by your health-care provider. |
| Diagnostic testing |
| OHIP-funded diagnostic testing (usually through chorionic villus sampling or amniocentesis) is the only way to know for sure if your baby has a chromosome difference during the pregnancy. If you wish to have a diagnostic test, you need to be referred to a genetics specialist in your area, who can arrange it for you. |
| No more testing during the pregnancy |
| If that is your choice, there is no further testing done even after after the baby is born, unless there are other concerns. |
You can also decide to have a detailed anatomy ultrasound. This ultrasound checks how the baby is growing and developing, and is done at 18-22 weeks of pregnancy (in the second trimester). This ultrasound can give you additional information; however, a normal ultrasound does not mean the baby does not have trisomy 21 or trisomy 18.
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