Ultrasonographic measurement of fetal nuchal skin to screen for chromosomal abnormalities

OBJECTIVE: The purpose of this prospective investigation was to determine the utility of ultrasonographic measurement of the fetal nuchal skin in screening for chromosomal abnormalities. STUDY DESIGN: In 1510 patients undergoing genetic amniocentesis at 14 to 21 weeks' gestation, the fetal nuchal skin fold was measured. A measurement of ò6 mm was considered abnormal. RESULTS: In fetuses with normal karyotype the nuchal skin increased with advancing gestational age (r = 0.45, p < 0.001). Only 27 fetuses with normal karyotype (2.0%) had an abnormal nuchal skin thickness. Fifty-seven fetuses had abnormal karyotype. Eight of 14 fetuses with Down syndrome had abnormal ultrasonographic findings; four had increased nuchal skin as the only ultrasonographic abnormality. Increased nuchal skin alone, in the absence of other ultrasonographic dysmorphologic features, did not help to identify fetuses with other abnormal karyotypes. CONCLUSION: Nuchal skin thickness is a useful noninvasive measurement to screen for Down syndrome but does not help to identify fetuses with other chromosomal abnormalities. (AM J OBSTET GYNECOL 1994;170:583-6.)