signs to look for on baby with Edwards syndrome

Hello! I'm 31 and currently 17+1 weeks pregnant. I got pregnant thanks to IVF. The triple-screen done at 16th week of pregnancy showed lower levels of hcg, but due to IVF incorrect dating of the preganancy can be excluded. The test placed me a low risk for trisomies 13, 21 and 18 and neural tube defects. However, I got recommendation for detailed ultrasound screening to search for the signs of Edwards syndrome. I'm confused about placing me low risk for trisomy 18 and at the same time sent to screen further for Edwards syndrome. If I understand correctly, there can be mosaic with that trisomy. Can this syndrome be detected by amniocenthesis at least if ultrasound doesn't help? I have to add that I had combined 1st trimester screening (blood work and ultrasound, which is said to be 90% precise method) and it showed no problems at all. Further, I would like to ask what can betray the Edwards syndrome in the baby at this stage of pregnancy? The amniotic fluid seems to be at normal level, the uterus seems to be normal size, and the baby still looks a few days ahead of his/her gestational age (had a breef ultrasound couple of days ago due to sudden lack of activity, but baby looked fine, I guess only felt I was stressed out). Does it really look like Edwards syndrome? I've read that babies with Edwards syndrome are small, fail to thrive. But can that baby at this point of pregnancy be bigger for gestation age and at the same time have indeed Edwards syndrome? Thanks already in advance.

[Jordanna Joaquina, MS, CGC]

Trisomy 18 (also known as Edwards syndrome) is associated with mental retardation and physical abnormalities. Some common physical abnormalities can include:

- low birth weight
- low set ears
- small head (microcephaly) that is abnormally shaped
- small jaw (micrognathia)
- small mouth
- clenched fists with overlapping fingers
- congenital heart defects
- kidney defects and problems
- clubfoot
- underdeveloped fingernails
- undescended testicle (cryptorchidism) in males
- unusual shaped chest (pectus carinatum)

Amniocentesis is a diagnostic testing procedure typically performed between 15 weeks and 23 weeks gestation for the diagnosis of fetal chromosome abnormalities, open neural tube defects and/or other genetic diseases (if indicated). It tells (with greater than 99% accuracy) whether a pregnancy is affected or is not affected with Down syndrome, Trisomy 18 and many other chromosome abnormalities. It tells (with greater than 90% accuracy) whether a pregnancy is affected with an open neural tube defect. This procedure involves the removal of a small amount of amniotic fluid from the uterus through a needle inserted into the lower abdomen. The average risk for miscarriage is less than or equal to 0.5%. If performed before 15 weeks gestation, the risk of miscarriage may be increased.

We recommmend that you meet with a genetic counselor who can review your screening results, personal history and family history and provide a more accurate risk assessment. A genetic counselor can discuss the benefits and limitations of screening versus diagnostic testing. You find a genetic counselor at the National Society of Genetic Counselors website or through companies like mine, AccessDNA.