I am 23 weeks. Does a 3.6 mm fetal nasal bone mean Down's?

Question

Hi doctor,

My quadruple test is normal. After 23 weeks of gestation, I took an anomaly scan, which shows 3.6 mm nasal bone. Is the nasal bone underdeveloped? What are the chances of Down's syndrome?

We do not want to get an amniocentesis test done as it increases the chance of miscarriage. Previously, I had a miscarriage as the fetus did not have a heartbeat.

Is there any other way to diagnose Down's syndrome?

Please help.

Answer 1

Hi,

Welcome to icliniq.com.

The nasal bone thickness is relevant only between 11 to 13 weeks pregnant scan where it should be less than 0.08 inches. Nasal bone thickness at 23 weeks gestation is irrelevant. If the quadruple test shows low risk of Down's syndrome, then amniocentesis (a test used to detect fetal abnormalities) is not recommended.

However, the only way to check Down's syndrome can be amniocentesis or CMA (chromosomal microarray) where fetal cells are separated from the mother and karyotyping is done.

I hope this answers your query.

Thank you and take care.

Answer 2

Hi,

Welcome back to icliniq.com.

The nasal bone length is not a soft tissue marker of Down's syndrome. It is the thickness, which is important. As the other markers and the nasal bone length are normal, the chances of Down's syndrome are negligible.

The quadruple marker graph(attachment removed to protect patient identity) is well below cut off, so unlikely that the child is Down's syndrome.

I suggest you take rest for a few days.

Thank you and take care.