Screening and diagnosis of chromosomal abnormalities in a foetus has seen a dramatic shift over the last 30 years or so.
Identifying high-risk women for aneuploidies based on maternal age alone has a poor detection rate. Assessment of foetal nuchal translucency and first trimester serum biochemistry has proven to be a far superior screening test detecting 90% of foetuses with chromosomal abnormalities at a false positive rate of 3-5%. A risk assessment calculator designed by the Foetal Medicine Foundation (FMF) London is used to calculate the individual risk. Only a handful of Foetal Medicine centres in Abu Dhabi have this risk assessment tool, one of which is Danat Al Emarat Hospital for Women and Children.
Dr Gowri Ramanathan, Head of ObGyn, Director of Foetal Medicine, Danat Al Emarat Hospital for Women and Children, Abu Dhabi, UAE, will be deliberating on aneuploidy screening in pregnancy at the Obstetrics and Gynaecology Conference during the Arab Health Recruitment & Training Fair from 18-20 October 2014 at the Abu Dhabi National Exhibition Centre.
According to Dr Ramanathan, “This new method of risk assessment has resulted in a shift to first trimester diagnostic testing by way of chorionic villus sampling (CVS) in the high risk group of women identified by screening with nuchal translucency and serum biochemistry, and also far less diagnostic testing, which itself carries a risk of miscarriage. The nuchal translucency (NT), which is the fluid behind the foetal neck, is measured between 11-14 weeks to determine the risk of the foetus having not only a chromosomal abnormality, but also cardiac, other structural abnormality in the foetus, or a genetic disorder. This is particularly prevalent in the UAE that has high consanguinity rates.”
A new high performance test, the non-invasive prenatal testing by analysis of cell free fetal DNA in maternal blood, has been shown to have a detection rate of over 99% at a false positive rate of less than 1% for trisomy 21 and 18. The value of this test has been proven in high-risk groups, and can be considered as a primary screening test in women at increased risk of chromosomal abnormalities
“Whilst I was the Director of Foetal Medicine at Corniche Hospital in Abu Dhabi, a review of foetal medicine statistics showed that the number of women who had risk assessment using nuchal translucency was only 6%,” says Dr Ramanathan. “Furthermore, of the babies that died in pregnancy or soon after birth, only 10% of these pregnancies were booked before 12 weeks of pregnancy and only 30% before 20 weeks. These are significant figures that need to be addressed.”
With the British and American Colleges of Obstetricians and Gynaecologists recommending that all women, regardless of maternal age, be offered prenatal assessment for aneuploidy, the UAE needs to benchmark this to ensure women are better informed and able to make their own choices about their pregnancy.