الفهرس 
Phenotypes, genetic and molecular basis of Down syndromeOnly 14 pages are availabe for public view
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Abstract
Summary
The current study was conducted to evaluate usefulness of ductus venosus pulsatility index, reversed a wave, nuchal translucency, and nuchal fold thickness in predicting Down syndrome and adverse perinatal outcome in 85 high risk pregnancies recruited from the Antenatal Clinic and Medical Genetics Center of Ain Shams University.
Ductus venosus Doppler ultrasound blood velocity waveforms and pulsatility index were obtained prospectively in 85 consecutive singleton high risk pregnancies. Waveforms were classified either as normal in the presence of a positive A-wave, or as abnormal if the a-wave was absent or negative. Nuchal transluceny thickness was obtained for all cases recruited during 1st trimester and considered abnormal when ≥2.5 mm. Nuchal fold thickness was obtained for all cases recruited during 2nd trimester and considered abnormal when ≥ 6 mm.. The outcome of these pregnancies was assessed.
The sensitivity, specificity and positive and negative predictive values for the detection of adverse perinatal outcome of increased nuchal translucency thickness, increased ductus venosus pulsatility index, abnormal ductus venosus a- wave and increased nuchal fold thickness were determined.
The mean age of participants, mean marriage duration, and gestational age were 32.5 ± 6 years, 7.1±3.3 years and 14.5±2.1weeks respectively. 92.95% of participants were house wives, only 2.4% were smokers and 90.6% of them did not have any medical disorder.
The mean Ductus Venosus pulsatility index was 0.91±0.41 among the studied sample; Nuchal transluceny was 1.6±0.4 mm among participants recruited in 1st trimester. The Nuchal fold thickness was 4.2±1.4 mm among participants recruited in 2nd trimester.
Seventy one (83.5%) of our participants had at least one previous child with Down syndrome. Consanguinity was present in 17.6% of the participants. Family history of Down sydrome was present in 9.4% of cases, Family history of other congenital anomalies was present in 5.9% of cases, and Parents chromosomal aberrations (balanced translocation) was relevant in 3.5% of the participants.
The abnormal, DV PI, reversed DV a- wave, increased NT thickness, and NF thickness was present in8.24%, 8.24%, 5%, and 8.89% respectively.
Down syndrome was found in 1.2% of current pregnancy outcome, while, cystic hygroma was found in 1.2%, cystic hygroma with hydrops was found in 1.2%, skeletal dysplasia and renal agenesis was found in1.2% missed abortion was found in 3.53%.
The DV PI of the only detected fetus with Down syndrome was 2.6, a wave was reversed, and the NF thickness was 6.6 mm.
There is a highly significant difference between normal outcome pregnancy and abnormal outcome pregnancy regarding mean DV PI and NF thickness while no significant differences regarding NT thickness.
Both ductus venosus PI and reversed A wave were 71.4% sensitive, 97.44% specific, with positive predictive value 71.43% and negative predictive value 97.4% for predicting abnormal pregnancy outcome.
The increased NF thickness (≥6 mm) in the second trimester was 80 % sensitive, 100 % specific, with positive predictive value 100% and negative predictive value 97.56% for predicting abnormal pregnancy outcome.
The increased NT thickness (≥2.5 mm) in the first trimester was 50 % sensitive, 97.36% specific, with positive predictive value 50% and negative predictive value 97.36% for predicting abnormal pregnancy outcome.