Case Study

35 year old, Caucasian female, gravida 1, Para 0. LMP consistent with 12 weeks and 4 days.

A review of the couple’s family history shows a first cousin once removed with Asperger syndrome. It was explained that the cause of autism spectrum disorders is not fully known at this time and that there is no prenatal testing available at this time.

Patient received genetic counseling regarding increased risk of fetal chromosome abnormalities associated with advanced maternal age. Based on the patient’s age of 35 at the time of delivery, the first-trimester risk of Down syndrome was 1 in 238 (0.42%) with a 1 in 110 (0.9%) risk for any chromosome abnormality. The risks, benefits and limitations for available prenatal screening and diagnostic test were reviewed, including nuchal translucency ultrasound with first trimester biochemical screening, MSAFP only screening, level II ultrasouond, CVS, amniocentisis, and maternal serum screening with cell free fetal DNA. The patient elected to have the first trimester screening ultrasound with nuchal translucency (NT), nasal bone (NB) and biochemistry.

CRL measured 59.3 mm. The NT measured 1.8mm. The NB appeared to be absent. It was explained that although an absent nasal bone can be associated with an increased risk for Down syndrome, it can also be a normal variant.   The  laboratory reported her free Beta hCG was 1.73 MoM and PAPP-A as 1.09 MoM. Risk after screening was 1 in 33 for Down Syndrome and 1 in 9601 for Trisomy 18/13.  The patient elected to pursue diagnostic testing at 16wks. An amniocentesis was performed. The lab reported a female fetus with normal karyotype 46, XX.  Ultrasound at 20weeks showed normal anatomy with persistent hypoplastic nasal bone.

Patient Outcome
The patient had a spontaneous vaginal birth at term, baby girl weighing 7 lbs 8 oz., no phenotypic abnormalities were reported.