Dual test is a screening test done to screen for chromosomal defects, most common of which is trisomy 21
(down's syndrome). I don't want you to get worried about this for many reasons:
- May be it is the policy in your country to have this test as routine.
- May be you are over 35 years where it becomes more indicated.
- This test is a screening test, meaning that if it is negative the abnormality is excluded, while if positive the abnormality is likely but not sure until confirmed by a further diagnostic test (i.e. it may be false positive).
If it is not routine in your country and you are not over 35 years, the sonographer may have seen something abnormal most important is increased NT ( nuchal translucency ).
I advise you to ask your obstetrician before doing this test because it is relatively expensive.
If it doesn't matter to you wether it's a Down or a normal baby, then there is no need to do this test and a detailed anomaly scan at 18-22 weeks will be enough.
I hope these words were usefull to you and I wish you best luck with your pregnancy
Dr. Ahmed Bahaa.