First trimester screening

early 11-14 week scan

Understanding the Down's syndrome risk
The risk for Down's syndrome is calculated using the mother's age and the measurement of the fluid at the back of the baby's neck - termed the nuchal translucency. This measurement can only be taken from 11+0 weeks until 13 weeks + 6 days. The ideal time is during the 12th week of pregnancy.

Women booking at the RVI
If you are already booked to deliver at the RVI then you will be asked if you wish to have the risk of Down's syndrome calculated at your routine 11 to 13+6 week dating scan. You do not need to pay to have this performed privately.

We are a recognised centre for Down's syndrome screening

The unit is accredited with the Fetal Medicine Foundation to perform the nuchal translucency measurement and our performance is and registration is reviewed each year.

There are plans for other hospitals in the Northern Region to develop a nuchal translucency service but at present we are the only hosiptal offering this service routinely.

What is the difference between a screening test and a diagnostic test?

The nuchal translucency measurement is a screening test and will not identify every baby with Down's syndrome. We estimate that it will pick up 8 out of 10 affected with Down's syndrome (80%), which is more than the maternal serum screening offered by most hospitals in the region at 16-18 weeks.

The test will either place you in a high or a low risk group for Down's syndrome. If you are in a high risk group we recommend that you consider having a diagnostic test. A diagnostic test examines the chromosomes of the baby and states whether the baby does or doesn't have Down's syndrome.

What are the diagnostic tests?

From 11 weeks a sample from the placenta can be taken. This is called a chorionic villus biopsy or CVB. The fetal medicine unit at the RVI is the only hospital in the Northern Region where this is performed.

Alternatively, from 16 weeks of pregnancy a sample of the amniotic fluid an 'amniocentesis' may be taken.

What can be done to further inprove the pick-up of Down's syndrome?
You may use your 11-13+6 week scan report and combine this information with a blood test taken after 10 weeks of pregnancy- and sent to Leeds for analysis. The results from this are combined with the nuchal translucency measurement to give an improved pick-up for Down's syndrome. The Leeds Screening Unit have a separate charge for this service.

To arrange this, ask your community midwife to request a blood test pack from the Leeds Screening Centre. Your blood test can be taken by your midwife from 10 weeks. We will inform you of your nuchal result and Leeds will combine this into a single result for the risk of Down's syndrome.

Click for further detailed information from the Antenatal and Newborn Screening Programme Website