Vanishing Twins Screening Positive Result

If you have a "vanishing twin" pregnancy, your prenatal screening test might have been a 11-14 week (nuchal translucency) ultrasound followed by Second Trimester Screening (STS). Or you might have had Second Trimester Screening (STS) on its own. Either way, your results are either "screen negative" or "screen positive". 

Choose your result to learn more about what it means and next steps:

Screen Positive

A "screen positive" result means there that there is a higher chance for the baby to have trisomy 21 (Down syndrome) or trisomy 18 (Edward syndrome). It does not mean that the baby definitely has one of these chromosome differences.

Most of the time when there is a "screen positive" result, the baby does not actually have trisomy 21 or trisomy 18. This means that the result is usually a false positive.

Contact Us

Prenatal Screening Ontario 
CHEO Research Institute 
Centre for Practice-Changing Research Building 
401 Smyth Road 
Ottawa, ON K1H 8L1

pso@bornontario.ca

Information line
Phone: 613-737-2281
Toll-Free: 1-833-351-6490

Monday to Friday, 9:00 AM to 3:00 PM EST

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Virtual educational sessions on prenatal screening and nuchal translucency quality assurance are available upon request for health‑care providers.

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