Can Increased Body Mass Index Prevent Adequate Ultrasound Examination for Trisomy 21 Risk Assessment?
Condition: Ultrasound Quality
MeSH terms: Down Syndrome; Trisomy
Study type: Observational

Summary: 
      Determine Cutoff BMI at which transabdominal sonography (TAS) is not satisfactory for
      aneuploidy risk assessment.
    

Detailed description: 
      Obesity is a common public health problem which is increasing worldwide at an alarming rate.
      According to National nutrition survey statistics of 2007, the prevalence of obesity in the
      kingdom of Saudi Arabia was 23.6% in women and 14% in men. Also the prevalence of overweight
      in the Saudi community was determined to be 30.7% for men as compared to 28.4% for the women.

      First trimester screening between 11-14 weeks gestation is known to be an effective and
      reliable screening test for Down syndrome and trisomy 18.First trimester screening allows
      earlier identification of the pregnancy at risk for fetal aneuploidy and anatomic defects,
      particularly, cardiac anomalies, therefore, providing an option of earlier diagnosis by
      chorionic villus sampling and analysis of amniocytes.

      The well-known association of obesity during pregnancy with a variety of maternal and fetal
      complications increases the importance of early aneuploidy screening.

      Fetal aneuploidy risk assessment is based on a combination of maternal age, prior affected
      pregnancy or family history, maternal serum biochemical tests and fetal ultrasound markers.

      The impact of obesity on the quality of prenatal ultrasound examination is well established
      with a greater risk for suboptimal visualization, in particular, the fetal cardiac structures
      and the craniospinal structures only when body mass index above the 90th percentile.

      The quality of prenatal screening for aneuploidy via nuchal translucency thickness
      measurement is significantly limited among obese pregnant women, thus, increased risk of
      fetal anomalies.

      Gandhiet al, have noted that increased BMI is not associated with suboptimal visualization of
      nuchal translucency, but it is associated with a longer time to perform the first-trimester
      ultrasound examination for aneuploidy risk assessment, increased need for transvaginal
      ultrasound examination for optimum nuchal translucency visualization.

      There is evidence suggesting that fetal anatomic evaluation in the low-risk gravida can be
      better accomplished in the first trimester using the transvaginal route, providing a valuable
      option for obese patients.
    

Intervention name(s): ultrasound
Intervention type(s): Other
Intervention description(s): trans abdominal or trans vaginal ultrasound to detect some of the soft markers of trisomy screening
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Inclusion criteria will consist of women who have a live, intrauterine, singleton pregnancy
        between 11- 14 weeks gestation.
      
Keywords: ultrasound; trisomy screening; obesity