Nasal Bone

[nyleelee68]

I am 39 years old and almost 35 weeks pregnant.  My original ob/gyn gave me NO prenatal tests, not even blood work was done.  I had a 20 week anatomic scan and was told everything looked great.  7 full weeks later I was told to have a fetal echo, and that they did not see the nasal bone.  Fetal echo was normal. I had another ultrasound at 27 weeks again told no nasal bone visualized.  I have since switched doctors and have been a total wreck thinking my baby has down syndrome.  From everything I read on the internet, it's guaranteed. There are no other markers, and for some reason, my new doctor is not worried. I had a 3d and 4d sonogram done at 28 weeks and he looks perfect.  I have over 200 pics and a 45 minute dvd, and no anomalies are seen.  Is it possible for a baby to have either no nasal bone or a very small one and not have down sy ndrome?  Please, if you could help me, I would so appreciate it.  I have been going through hell.

[Lisa Kessler, MS, CGC]

It can be extremely stressful when something is found on a routine ultrasound.  There has been some research that shows that absence of the nasal bone at 10-12 weeks gestational age is associated with Down syndrome.   You did not mention your race, and that can impact the nasal bone finding.  The following study was conducted with Caucasian individuals.   This study found that the ultrasound finding of absence of the nasal bone picked up 82% of pregnancies with Down syndrome, but had a false positive rate of 8.3%.  In other words, some of the pregnancies thought to have no nasal bone did not have Down syndrome.  The other finding of these studies is that even skilled ultrasonographers experienced difficulties in nasal bone assessment.  Another study found more pregnancies with an absent nasal bone in the first trimester of women who are of Afro-Caribbean and Southern Asian ancestry.

At age 39, the chance to have a baby with a chromosome problem is 1 in 80.  It is reassuring to hear that the fetal echo was normal.  You wrote that the ultrasound at 28 weeks looks perfect, and that sounds reassuring as well.   I hope that this has been helpful.  I wish you the best with your pregnancy.    

[vampares]

If nothing else indicates Down's Syndrome I would not be worried about this.  The age relation to DS appears to be a myth from what is now know about DS, except in the few (8%) cases where the male is the carrier.  That does not eliminate the possibility of other genetic disorders.  The scope of what medicine will do to insure health pregnancy is limited.  That is something they have decided to leave up to the parents.