OP12.04: The frontal fetal facial (FFF) angle in the second trimester measured by 3D ultrasound in normal fetuses and fetuses with Trisomy 21

Abstract

The aim of this prospective study was to compare the FFF angle (forehead-nose-mandible) in normal fetuses and fetuses with confirmed Trisomy 21 in the second trimester. In 80 normal fetuses and 42 fetuses with trisomy 21 the FFF angle was measured in the multiplanar 3D mode after aligning the fetal head into an exact upright position and demonstration of the true profile. All scans were performed using E8 GE equipment (Zipf, Austria) with a 5–8 MHz 3D abdominal transducer. Gestational age was between 14 and 27 weeks of gestation. Only in 7.5% (6/80) of the normal cases the FFF angle was measured >145° but not higher than 150°. In Trisomy 21 fetuses 57.1% (24/42) of the cases showed a FFF angle >145° and in 19.0% (8/42) of the Trisomy 21 cases the FFF angle was higher than 150°. Fetuses with Trisomy 21 show higher FFF angles than normal fetuses due to a flat profile. FFF angles >145° should be considered suspicious for Trisomy 21 while values ≤145° do not exclude Trisomy 21 in the second trimester.