21 Week Scan

[JoFP]

I have just had my 21 week scan and have been told that my baby has mild dilated renal pelvises (at 6mm vs the normal 5mm).  Also on the Anomaly scan results I see that although within the 5th to 95th centile range the Biparietal Diameter is at 52 mm (so slightly more than the 50 mm for 21 weeks) and the Femur length is at 32.9mm (so slightly shorter than the 34mm for 21 weeks).  Looking at each in isolation I see references to Down's Syndrome  - however my risk was 1 in 15000 so should I be worried?  Should I now be asking for an amniocentesis or is the risk extremely low?

[Elaine Brown, MD]

Hi!
All of the things that they mentioned on your scan are  VERY common in NORMAL babies.  I would not recommend an amnio to my own patient-even if she was over 35--based on those findings alone.  Remember that the baby is moving while they are taking the measurements, and turning the probe just slightly could change the measurement by a centimeter or two.  If you had another scan tomorrow, it would very likely turn out differently.  It sounds like you have a healthy normal baby--boy or girl?

Congratulations!
Dr B

[JoFP]

Thank you so much this really was reassuring and mad me want to cry with relief.  We are going to have a baby boy - obviously very excited but as first very worried.

Thanks again.