First Trimester Screening (FTS)
All women, whatever their age, have a small risk of delivering a baby with a chromosomal abnormality. pregnancy scans 12 weeks nuchal scanTrisomy 21 (Down Syndrome) is the name given to a condition where a baby has an extra copy of Chromosone 21 in every cell. The extra chromosome causes physical differences, developmental delays and a tendency toward certain health problems. This condition is incurable, but testing during pregnancy gives parents the chance to prepare for the unique needs of a child with birth defects, as well as identifying any specific abnormalities that may require medical care after birth.
First Trimester Screening (FTS) does not guarantee a normal baby. Therefore you should carefully consider the advantages and disadvantages of screening test such as FTS compared with a diagnostic test such as CVS or amniocentesis. One way of estimating the chances of your baby having a chromosomal problem is the first trimester screening test of the nuchal translucency measurement combined with a blood test. This test is carried out between 12 weeks and 14 + 6 weeks gestation.
The Harmony Prenatal Test that we can also offer is considered currently to have the highest accuracy in testing for various abnormalities.
Further below you can also find a variety of commonly asked questions about the nuchal fold scan.
Nuchal Fold Scan – 12 – 14 weeks
To include photographs and computerised report
Below is a video of one of our consultants, Prof. Fionnuala McAuliffe, explaining about nuchal fold scans
Overview of a Nuchal Fold Scan
The nuchal fold scan (nuchal translucency test) is performed to:
- screen for Down’s Syndrome and other abnormalities (the measurement of the fluid at the back of the baby’s neck can be an indication of a fetal abnormality or syndrome)
- to confirm the presence of certain vital parts of the anatomy such as the baby’s skull, brain, nasal bone, spine, heart, stomach, abdominal wall, kidneys, bladder, arms & legs.
Please note: A blood sample is also requested to help identify any abnormalities. Normally, bloods are taken ten days prior to the Nuchal Translucency Scan. These bloods will be taken in the Phlebotomy Clinic in the Private Suite at No. 60 @ National Maternity Hospital. The results of these bloods will be available at your scan appointment. The cost of the bloods are included in your scan. The Nuchal Transluceny scan cannot tell for certain if your baby is affected. However, it can help you decide whether or not to have a diagnostic test.
Nuchal Fold Scan – How Is The Risk Assessed?:
Each woman will be given an estimate of her individual risk for their pregnancy. Your risk is assessed by taking into account the following:
- Age of the mother – Amount of fluid behind the neck of the fetus (nuchal translucency).
Fetuses at risk of Down Syndrome tend to have a higher amount of fluid around the neck. Babies accumulate fluid at the back of their neck (nuchal) during the first trimester. As a result of this fluid, the baby’s nuchal fold increases in thickness each day of gestation until the fluid disappears around the 15th week. Researchers have established an average or “normal” thickness for each day during the three weeks you are eligible for the screening If your baby’s nuchal fold is thicker than average, he or she is considered at a higher risk for an abnormality; if it’s thinner, his or her risk is lower. A more accurate risk assessment, combines the Nuchal Translucency scan with the results from two bloods tests that measure the levels of pregnancy associated plasma protein – A (PAPP-A) and human chorionic gonadotrophin (hCG) in the mothers blood. Abnormal levels of these two pregnancy related substances may indicate a problem. Combining the scan and blood test gives a more accurate result than either the ultrasound part or the blood part of the test done on their own. You must be at least 10 weeks gestation or more for the blood sample to be taken. The Nuchal Translucency scan cannot tell for certain if your baby has a chromosonal defect, however, it can help you decide whether or not the chance of your baby having a chromosonal problem is high enough to warrant having an invasive test such as CVS (Chorionic Villus Sampling) or Amniocentesis. However, these tests carry a slight chance of miscarriage and therefore options should be discussed with their healthcare professional. CVS is performed in the 13th week and amniocentesis around 15th or 16th week of pregnancy.
Nuchal Translucency Test-What To Expect
Who Performs Your Nuchal Fold Scan
The ultrasound portion of the Nuchal Translucency test is done by a sonographer/obstetrician or radiographer who is trained for this specific screening.
How do you prepare for this scan?
There is very little preparation needed. You should have some fluid in the bladder but not be uncomfortably full. Drinking fluids prior to the examination will enlarge the bladder. The bladder is used as an acoustic window to improve the image quality and it also improves the position of the baby. It is a good idea to wear comfortable clothing that gives easy access to your lower abdominal area.
How is the nuchal scan performed?
The scan is performed by applying a warm gel over the patient’s lower abdominal area. A transducer (a smooth hand held device) is moved gently across the abdomen with a sliding and rotation action to scan the baby through the tummy. It can sometimes be difficult to accurately measure the Nuchal Translucency because of the position of the fetus. In this case the sonographer/radiographer will explain that a transvaginal ultrasound is needed and will request your permission to do so. A transvaginal ultrasound involves a small specially shaped transducer to be inserted into the vagina. Because the transducer is closer to the fetus it can provide clearer images.
What are the risks associated with the nuchal translucency test or nuchal fold scan?
There are no known risks to performing trans-abdominal ultrasound which uses sound waves to obtain pictures or images. There is no radiation involved. Nuchal Translucency testing is non invasive and poses no risk to the foetus or similarly no risk to you or of miscarriage. Should you have First Trimester Screening (FTS)? Only you can decide whether or not to have FTS. To book an Nuchal Fold Scan please call (01) 663 5060 or use the Make a Booking online form. This scan is from 11 weeks to 14 weeks.
What is a thick nuchal fold?
When the nuchal fold has a thickness of over 6 mm, the baby is considered to have a high chance of fetal abnormalities such as Down’s Syndrome, heart problems and other anomalies.
Usually the nuchal fold grows in proportion to the developing baby. For example, when a baby measures between 45 to 84 mm (1.8 to 3.3 inches), a nuchal fold of under 3.5 mm would be considered to be within the normal range.
What is normal nuchal translucency?
The nuchal translucency normally develops in proportion to the growing baby. 90% of babies with a NT measurement within the range of 2.5 mm to 3.5 mm will not develop Down’s Syndrome.
What is normal nuchal fold thickness at 12 weeks?
When the baby has reached 12 gestational weeks of pregnancy, the average range for nuchal thickness comes in at 2.18 mm. However statistics have also revealed that 13% of babies who present with a NT of over 2.5 mm at 12 weeks are born chromosomally normal.
How accurate is the nuchal translucency test?
The nuchal translucency test is considered to be between 70% to 80% accurate. When performed along with an ultrasound and blood tests, the accuracy rises to between 80% to 90%.
The Harmony Test is a more accurate and non-invasive alternative.
When should nuchal translucency be done?
The nuchal translucency test needs to be carried out between gestational weeks 11 to 14, as this is the period when the neck of the baby is still transparent.
What causes Down syndrome during pregnancy??
Trisomy 21 is the more common version of Down’s Syndrome. This is when people have 47 chromosomes er cell, as opposed to 46. Trisomy 21 occurs when nondisjunction takes place – this is an error in how the cells divide.
How can you prevent Down syndrome during pregnancy?
The best way to try to prevent Down’s Syndrome is by planning ahead before conception. Taking 400 mcg (micrograms) of folic acid each day ideally at least a full month if not longer before conception. Then you need to continue to take in during your early pregnancy.
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All articles on the blog and website are intended as information only. Please do not consider any of the information provided here as a substitute for medical advice. At all times seek medical advice directly with your own doctor and medical team.