Fetal ear assessment and prenatal detection of aneuploidy by the quantitative three-dimensional ultrasonography

The purposes of this study were to use quantitative three-dimensional (3-D) ultrasonography to establish the normal charts of three fetal ear-growth i ndexes, (ear length, ear width and ear area), and to validate their efficac y in the prenatal diagnosis of fetal trisomies, either separately or as a c ombination. Using quantitative 3-D ultrasonography, we performed a prospect ive study to measure the three fetal ear growth indexes (i.e., ear length, ear width and ear area) in 129 singleton pregnancies, including 122 normal fetuses and 7 trisomies, The ear shape was also evaluated in these fetuses using both 2-D and 3-D ultrasonography. Our results showed that: First, 3-D ultrasonography offers better visualization and easier evaluation of fetal ears than 2-D ultrasonography, Second, when using the quantitative assessm ent of 3-D ultrasonography, the measurements of ear length, ear width and e ar area were all correlated significantly with gestational age in normal pr egnancies (r = 0.881, 0.848, and 0.890, respectively). In addition, 3 of 7 fetal trisomies had ear length below the tenth percentile, 1 had ear width below the tenth percentile, and 2 had ear area below the tenth percentile. Furthermore, with the combination of these three measurements, (including e ar length, ear width and ear area), the sensitivity in detecting fetal tris omies was elevated to 57.1% and the specificity was 83.2%. In conclusion, 3 -D ultrasonography reduces the limitations of 2-D ultrasonography in the ev aluation of fetal ears. However, fetal ear measurement may not be used as a single ultrasonographic parameter in identifying aneuploid fetuses. We rec ommend using the combination of these three ear growth indexes to enhance t he detection rate of aneuploidy, (C) 2000 World Federation for Ultrasound i n Medicine & Biology.