Nuchal Scan

What is Down's Syndrome and your risk explained

All women, whatever their age, have a small risk of delivering a baby with a physical and/or mental handicap.  In some cases the handicap is due to a chromosomal abnormality in which there is an extra chromosome 21 (Trisomy 21).

Down's syndrome is one of the most common genetic abnormalities affecting 1 in every 700 births worldwide with the risk increasing with maternal age.

At Georges Memorial Medical Center this service is currently available in our Lekki Centre

Why consider Down's Screening?

What are the advantages for ladies over 35 who are considered 'high risk' anyway?

Older mothers are more likely to have a Down's syndrome baby but age alone will only pick up 30% of cases. Many older mums are carrying perfectly healthy babies but may feel the need to have a test to exclude DS; By having an invasive test such as amniocentesis means putting the baby at risk resulting  in miscarriage. By assessing your baby with ultrasound and analysing your blood, you can be given an adjusted risk factor for your  pregnancy which will pick up 90% of Down's babies.  If the results from these tests are good, this will mean that you are no longer considered as high risk and therefore may opt against invasive testing.

What are the advantages for younger mums?

On age alone as a younger mum, you are less likely to be carrying a Down's baby, but the majority of Down's babies are born to healthy young parents without any known risk.2 This is largely because historically screening has been offered to the older age group. Any mum regardless of their age carries a risk of a chromosome abnormality such as Down's. By opting for Nuchal translucency screening, you can be reassured that your baby is not at increased risk.

Other advantages of ultrasound scanning in early pregnancy

In addition to calculating the chance of your baby having Down's Syndrome the scan has a number of other obstetric benefits:

• Date the pregnancy accurately
  This is particularly relevant for women who cannot recall the date of their last period, have an irregular cycle, or who have conceived whilst breast feeding or soon after stopping the pill.  We measure the size of the fetus and from this we calculate the expected date of delivery.
   
• Identify multiple pregnancy
  Approximately 2% of natural conceptions and 10% of assisted conceptions result in multiple pregnancy.  Ultrasound scanning can determine if you have twins and if both babies are developing normally.
  
• Detect certain major fetal abnormalities
  Some major abnormalities are visible at this scan.  However a full 20-week anomaly scan is essential.
• Diagnose early pregnancy failure
  In about 3% of women who attend for a nuchal scan it is found that the fetus has died, often several weeks before and without any warning. Couples will receive counselling as to the possible causes of this

Irrespective of whether or not you decide to have an early pregnancy scan, it is recommended that you have a scan at 20 weeks to check for different physical abnormalities.

Anomaly Scan

Medical file - Second trimester, weeks 13 to 26

Your 20-week scan

Most women are offered a detailed scan at about 20 weeks to see if the baby has developed normally; this is known as the anomaly scan. You will now be halfway through your pregnancy and your baby will be about 20cm (8 inches) long from head to toe, your bump will be growing rapidly and you will probably be feeling some of your baby's movements.