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Femur Length as Marker
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Femur Length as Marker

I am hoping that someone can answer my question:) I am 28 years old and have a 1/200 risk of down syndrome from the quad screen at 16 weeks. We opted out of the amnio but did a level 2 ultrasound. the baby's femurs measured in the 96th percentile at 20 weeks and the 86th percentile at 24 weeks.

Should I be concerned that they are getting shorter? I know that many babies with DS have normal femur measurements, but do they typically have long measurements? I'm just trying to prepare myself best as possible:)
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1227139 tn?1462338230
Hello Teacher98,

First welcome to the Ds community!  Your Ds risk of 1/200 is less then 1% which is great - it's 1/2 a percent in fact.  So that is still really good!  But, the reality is, odds are just odds, they are numbers complied from statistics.  My maternal risk was 1:385, and that was even after the first sets of screening by blood and the first ultrasound at 12 weeks for the NT scan, which was all normal.  Yet my son was diagnosed via Amniocentesis with Down syndrome!    What is helpful is knowing about markers and items that can be observed to give you a clearer more realistic picture.  So it's really good that you are asking about the markers.

You asked about the femur measurements.  As far as being marker, typically for Ds, the femur bone (as well as the other long bones like the humerus (upper arm) bone) will definitely be shorter - up to a few weeks or more behind.  They don't typically have long measurements.  When you asked if they are getting shorter, it's not that they are getting shorter per se, it's that they aren't growing in the same ratio as they would normally to stay in the same percentile.  So I think that is what you meant then it can be concerning.  The thing is, babies in the womb can have shorter then the "typical or corresponding gestation age length" one week and then the next time everything seem to be right on target.  The point in which you would have to be concerned is when it is consistently shorter then what would be considered "typical" for the gestational age.  If every week that you have an U/S the measurements are out by 2 weeks or more then it would be cause to look into it.  So knowing the percentile is great but it would be helpful to know exactly the corresponding gestational age that they are saying your baby's bones are measuring at.  Because the percentile you are listing is actually in a great range albeit that it's decreasing.  (Below the 50% percentile or more is more concerning.)  Also, different tech's measure differently.  I had two different technicians in the same day make different measurements that put our son way out of whack and the other put him in the typical range.  So that can be problematic too.  Remember also that having short long bones can be attributed to genetics (in the sense that maybe in your families long bones are shorter then "average".  It could be that your baby just measures shorter all around.  Simply having short long bones by itself isn't cause for alarm.  I would say if there are other markers, coupled along with short long bones over a period of time, then I would say that you might want to consider other testing or more frequent high level ultrasounds.  

The good news at this point (24 weeks) is, the radiologist definitely would have been been able to see other markers, if they are there.  I have a long list of markers that can be helpful for you if you would like to have it.  I have passed this list on to many mommies and they have asked their U/S tech to look over these areas when they are concerned about Ds.  The thing here to remember also is, while the list is pretty comprehensive, my son didn't show markers either until after I learned that he had Ds at 18 weeks.  Did you have your NT measurement done for your baby? (Nuchal Translucency Scan is performed between 11-14 weeks)  Did they tell you the measurement and if it fell into the "typical range"?

If you wish, I can definitely give you the list - just send me a direct message and remind me that you want the Markers-Characteristics list for Ds.

I really commend you for researching and trying to get as much information and be prepared as possible.  It was the one thing that made my life so much easier and also made me realize that having a son with Ds was not what I thought it was!  (I hope that you get the chance to take a look at my blog.  I tell mom's who are going through this worry to stop by and take a quick peak.  Seeing it in real life is much easier to digest then just having someone say to you, it's all good.)

If you need any other resources that I can pass onto you, please do not hesitate to ask me for them.  I have a lot of personal and professional resources - all positive and most importantly accurate.  Much of the information floating around out there is not accurate or positive.  So, if I can help, please let me know!

In addition to anything I have mentioned, please keep in mind, that while I or others may have extensive knowledge in many areas, you should always seek professional medical advice from your own physician, as it pertains to medical conditions or concerns.

Good luck, and if you have any other questions that I can help you with, please feel free to message me directly.

Sandi (Dragon1973)
MedHelp Genetics Community Leader;
Children - Special Needs Community Leader;
Down syndrome Community Leader & Ds Group Forum Founder/Moderator
Avatar m tn
I am from India. could you please mail me Markers-Characteristics list for Ds.
on my email id: rajul_gala22***@**** as I am going through the same anxiety right now.

Thank you
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