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Normal nuchal thickness measurements reduced Down syndrome risk in second-trimester pregnancies with an abnormal triple screen 9 That study had limited application because only crude group risk estimates and not individual Down syndrome odds could be derived using that information. Maternal serum screening (including triple screen) is now widely available 7 and, apart from maternal age, is the only other officially sanctioned Down syndrome screening method 8 By combining maternal serology and ultrasound biometry, Down syndrome screening efficiency can be improved further. The latter finding agreed with previously reported observations 5, 6. Humerus length and nuchal thickness measurements were the most important biometry markers for Down syndrome.
#Ultrasound screen marker trial#
Several studies have reported using ultrasound biometry markers for adjusting Down syndrome risk 1- 3 A large recent multicenter trial of 241 Down syndrome second-trimester fetuses found that 85% of the affected group had ultrasound abnormalities 4 Among Down syndrome cases without gross structural defects, 75% had subtle ultrasound markers or abnormal biometry.
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The model appears promising and should be evaluated in an independent data set. At a 10% false-positive rate, detection was 45.7% for the triple and 80.4% for the four-marker screen.Ĭondusions A new algorithm combining humerus length and nuchal thickness measurement with serum AFP, hCG and maternal age substantially improved Down syndrome screening efficiency compared with the traditional triple screen. The areas (SE) under the ROC curves were 0.75(0.04) and 0.93(0.02) for the standard triple and the four-marker screen, respectively (P < 0.001). The median maternal age for the study group was 35.0 years (14.0–46.0 years). The gestational age range for the study was 14–24 completed weeks. Results There were 46 cases of Down syndrome (1.9%) with 2391 normal singleton pregnancies in a referral population in which triple screen, fetal biometry and karyotype had been done. Sensitivity and false-positive rates at different Down syndrome risk thresholds were also compared. Receiver operating characteristic (ROC) curves plotting sensitivity against false-positive rate were constructed for each algorithm and the areas under the curves were compared to determine which was superior. A quadrivariate Gaussian algorithm was used to calculate individual Down syndrome odds.
#Ultrasound screen marker plus#
humerus length, nuchal thickness, AFP and hCG plus maternal age.
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alpha-fetoprotein (AFP), unconjugated estriol (E3), hCG and maternal age, was compared with the four-marker algorithm, i.e. Methods The Down syndrome screening efficiency of the triple screen, i.e. Objective To compare Down syndrome screening efficiency of the standard serum triple analyte screen to that of a four-component screen consisting of ultrasound biometry and serum markers in the second trimester.