Enhanced first trimester screening (eFTS) is a screening test that your provider can arrange in the first trimester of your pregnancy (from approximately 11 weeks 2 days to 13 weeks 3 days gestation). eFTS uses a combination of obstetric ultrasound and blood work to give information about trisomy 21 (Down syndrome) and trisomy 18 (Edward syndrome).

How the test works

If you choose to have eFTS, you will be scheduled for a nuchal translucency (NT) ultrasound and a blood test. The NT ultrasound and blood test do not have to be done on the same day. Depending on where your screening is performed, the bloodwork will measure the levels of 3 or 4 different hormones or proteins that are present in your blood at this point in pregnancy:

• pregnancy-associated plasma protein A (Papp-A) – a protein produced by the placenta
• human chorionic gonadotropin (hCG) – a hormone made by the placenta during pregnancy
• alpha-fetoprotein (AFP) – a protein produced by the baby's liver
• placental growth factor (PlGF) – a protein produced by the placenta

The results of the NT ultrasound and the blood work will be combined with your age (or the age of your egg donor) at delivery, to give you information about the chances for trisomy 21 (Down syndrome) or trisomy 18 in pregnancy.

It is important to remember that no screening test can give a definite “yes” or “no” answer about these conditions.

If Non-Invasive Prenatal Testing (NIPT) has already been initiated, eFTS should not be done. However, an NT ultrasound is still recommended as it can offer additional information about the health of the baby. 

The benefits of eFTS

• screening tests pose no risk to pregnancy
• early results allow for earlier decision-making about further testing & care

The limitations of eFTS

• screening tests do not give a “yes” or “no” answer, they will given information about the chances of having a baby with a specific condition
• screening tests are not 100% accurate – false positive and false negative results are possible
• cannot be done in a vanishing twin scenario

Screening results

Your eFTS result will be shared with your provider within 7-10 working days. Talk to your provider about how they plan to share these results with you.

When you receive your eFTS result it will say that you are a  “screen positive” or a “screen negative”.  The result will also give you a personalized likelihood that your baby has trisomy 21. For example, a possible result may be a 1 in 50 or 1 in 700 chance that the baby has trisomy 21. Your provider will review the result with you and make a plan for follow-up if necessary.

If your report does not include information about trisomy 18, you can assume you have a "screen negative" result for this chromosome difference. 

Detection rate

The detection rate of eFTS is 85-90%. This means that 85-90% of patients carrying a baby with trisomy 21 will get a screen positive result using eFTS. Because screening cannot detect 100% of cases, 10-15% of pregnancies with trisomy 21 will receive a screen negative result using eFTS.