abnormal ultrasounds

  Hello.  I am a 26 yr. old diabetic so when I became pregnant, my OB has followed me closely.  I saw him on my 9 week 0 day.  We did our first ultrasound and everything looked normal.  At 11 weeks 0 day, we did another ultrasound.  At this time he saw (and pointed out) what looks to be like a large fluid pocket on the babies neck (between the head and body on the back side).  Today is the beginning of my 12th week and we did another ultrasound.  We still see the same thing.  The doctor mentioned trisomy disorders. He now has me scheduled for either a CVS (which is going to be hard because of my weight) or an early amnio.  I have several questions.  My doctor said he has seen this on a couple of ultrasounds and everything turned out alright, but in a lot more cases, chromosomal abnormalities did exist.  What type of statistics are there about this?  My fetus looks normal otherwise, should I be very concerned?  (I am)  I have had one prior miscarriage (@ 8 weeks) and had such hopes of everything being OK.  I am young and so is my husband, what could have caused this?  Also, are there other chromosmal abnormalities besides trisomy disorders?  My husband and I had agreed when we first got married 7 years ago, that if anything ever was wrong in a pregnancy, we would terminate.  What are the defects that occur with trisomy disorders, can people live normal lives who suffer from them?  Please try to get me some answers...I am so confused, scared, and depressed.  I thought the diabetes was enough to worry about:)  
  Thank you so much for your time.
  Lori
Dear Lori:
The concern regarding a fluid collection in the neck area is cystic hygroma. This developmental anomaly is associated with chromosome anomalies about 70% and occurs as an isolated event in 30% of cases. When it is an isolated finding, the cyst usually grows smaller during pregnancy.
The commonest chromosmal anomalies are trisomy (three chromosomes instead of two) and trisomy 21 (Down Syndrome) is leading diagnosis in this category. The degree of developmental impairment ranges from severely handicapped to mildly affected and able to integrate into job and home activities. A second common association is with 45 X (the loss of one X chromsome) which has physical variations such as short stature and sterility because the ovaries are never able to make eggs and hormones.
Chromomal anomalies are diagnosed from the chorionic villous sample (CVS) or amniocentesis. Gathering good information before making any decisions about the pregnancy is very important.
It is normal to be frightened by the uncertainty that you are facing. The support of family and your healthcare providers are there for you.
Keywords: cystic hygroma
This information is provided for education purposes and is not a medical consultation. If you have specific questions, please contact your physician.