A Nuchal Translucency screening test for Down's Syndrome and two lesser known chromosome abnormalities Edward's and Patau's syndromes is not widely available on the NHS.
The screening involves a blood test and a highly specialised scan that is performed between 11 and 13 weeks and 6 days of the pregnancy:
- measuring the fetal size (crown rump length).
- presence of fetal heart activity.
- measuring the nuchal translucency
- blood flow through the tricuspid valve of the fetal heart
At your appointment you will be counselled and scanned by a consultant in Maternal and Fetal Medicine. At the end of the scan, an individualised estimated risk for Down's syndrome will be calculated and discussed with you together with information on any further investigations if .
It is important to realise Nuchal Translucency screening gives you a ‘relative risk’ value for the baby having chromosomal anomalies, such as Down’s Syndrome. In the great majority of cases, we hope that this will be reassuring. The only way to know definately is to have an invasive test, Amniocentesis or Chorion Villus Sampling (CVS) which carry a small risk of miscarriage and this is only usually offered if the risk is greater that 1 in 250.
The findings and the potential need for any further investigations will be discussed with you by a specialist in fetal medicine.
You will receive a CD and black and white (thermal) pictures of your baby together a medical written report. We will also ask if you would like a copy of the report sent to your GP.
For fees please see our Fee’s section on the left.
Please note that you do not need a GP referral.
We have a dedicated team of specialists and support staff waiting to help you.
Call us on 0121 454 7779
More about Nuchal Translucency
This measures the fluid at the nape of the neck in the baby between 11 and 13 weeks and 6 days.
It is important to understand that a certain amount of fluid may be normal. However, if this measurement is increased significantly this may indicate an underlying risk of a chromosome anomaly (for example Down’s syndrome) or possibly a structural anomaly (most commonly heart abnormalities, Tricuspid regurgitation – leaking heart valves).
Presence or absence of the nasal bone
Absence of this bone is associated with an increased risk of an underlying chromosome anomaly.
This information is used to calculate the risk of chromosome abnormalities. Nuchal translucency measurement is most accurate when used in conjunction with a maternal blood test which estimates hormones produced by the placenta (afterbirth) and baby. These hormones are called free Beta human chorionic gonadotrophin (βHCG) and PAPP-A (pregnancy associated plasma protein A).
What is Down's Syndrome?
Down's Syndrome is often referred to as Trisomy 21 and is caused by the presence of an extra chromosome 21 in the cells of the fetus, some times referred to as Trisomy 21, giving a total of 47 chromosomes.
This is a genetic accident that occurs at conception. Overall Down's syndrome occurs in 1:800 pregnancies, though as can be seen below this risk is increased, more likely, with increasing age. People with Down's syndrome may have learning disabilities, congenital abnormalities such as heart defects and Alzheimer's disease later on in life.
How likely is Down's Syndrome at birth?
| Maternal Age |
Risk of Down's Syndrome |
Approximate number of Down’s syndrome cases per 9000 pregnancies |
| Less Than 25 years |
1:1500 |
6 |
| 30 years |
1:900 |
10 |
| 40 years |
1:110 |
82 |
| All |
1:800 |
11 |
What is a Neural Tube Defect?
There are two kinds of Neural Tube Defects:
Babies with Spina Bifida have an opening in the bones of their spine, which usually results in damage to the nerves that control the lower part of the body. This causes weakness and paralysis of the legs.
In addition sometimes the bowel and/or the bladder can be affected. Babies with Spina Bifida are also more likely to have a collection of fluid on the brain - hydrocephalus, which can lead to mental handicap.
Babies with anencephaly have a large part of their skull missing and the brain is not properly formed. Babies with this problem always die before or very soon after birth.
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Nuchal Translucency Screening for Down's Syndrome