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Prenatal screening for fetal chromosomal abnormalities using ear length and shape as an ultrasound marker.

INTRODUCTION
To determine the range of fetal ear length and ear shape variability in healthy fetuses and in fetuses with aneuploidies in the population of patients of our institution and to evaluate the clinical value of fetal ear length and shape assessment in screening for fetal aneuploidies.


MATERIAL AND METHODS
Fetal ear length was determined in 210 healthy and 15 aneuploid fetuses of pregnant women undergoing targeted ultrasound examination. Fetal ear shape was assessed in the coronal section of the head and classified into one of three categories: flat, slightly protruding, markedly protruding and curved in 175 healthy and 14 aneuploid fetuses.


RESULTS
Fetal ear length showed significant positive linear relationship with gestational age, which could be described by the following equation: Ear length (mm) = 0.968566 x gestational age (weeks) - 4.81629. Fetal ear shortening below 79% of expected length yielded the sensitivity of 26.7% in the detection of fetal aneuploidy at the false positive rate of 4.8%. Finding of markedly protruding and curved ears predicted fetal aneuploidy with the sensitivity of 28.6% at the false positive rate of 1.7%. The combination of fetal ear shortening below 74% of expected length or markedly protruding and curved ears resulted in the sensitivity of 33.3% and false positive rate of 3.33% in the detection of fetal aneuploidies.


CONCLUSION
Fetal ear shortening has been confirmed as a marker of fetal aneuploidies. Abnormal fetal ear shape has been shown to constitute an additional marker of fetal aneuploidies, increasing the clinical value of fetal ear length measurements.