The association between an abnormal nuchal skin fold, trisomy 21, and ultrasound abnormalities identified during the second trimester of pregnancy.
Fetal echocardiography and a detailed non-cardiovascular ultrasound examination were performed prospectively between 14 and 23 weeks of gestation prior to genetic amniocentesis in 2800 consecutive fetuses at increased risk for trisomy 21 due to advanced maternal age or a low maternal serum alpha-fetoprotein. An abnormal nuchal skin fold was defined as >or=6 mm. Of 2800 fetuses, 23 (0.82%) had an abnormal nuchal skin fold. Seven of 35 fetuses (20%) with trisomy 21 and one of 12 fetuses (8.3%) with trisomy 18 had an abnormal nuchal skin fold. Of the 23 fetuses with an abnormal nuchal skin fold, seven (30.4%) had trisomy 21, one (4.4%) trisomy 18, one (4.4%), 46,XY,11p+ and 14 (60.8%) had normal karyotypes. The fetuses with trisomy 18 and 46,XY,11p+ had malformations of the cardiovascular and non-cardiovascular organ systems. Five of seven (71%) fetuses with trisomy 21 and an abnormal nuchal skin fold had abnormalities of both the cardiovascular and non-cardiovascular organ systems; one of seven (14.5%) had a heart defect only; and one of seven (14.5%) an abnormality of a non-cardiovascular organ system. Of the 14 fetuses with an abnormal nuchal skin fold and normal karyotype, seven had no additional abnormalities, six an abnormality of the heart, and one a non-cardiovascular defect. Fetuses with an abnormal nuchal skin fold had a significant increased incidence of trisomy 21 when a combination of cardiovascular and non-cardiovascular abnormalities were present compared to fetuses with no additional defects or a single defect of the heart or non-cardiovascular organ system (p = 0.001). In fetuses with an abnormal nuchal skin fold, the incidence of congenital heart disease was 6155, central nervous system defects 17%, hyperechoic bowel 8.7%, and renal abnormalities 17.4%. These findings would suggest that the fetus identified with an abnormal nuchal skin fold with additional cardiovascular and non-cardiovascular abnormalities has a greater risk for chromosomal aneuploidy compared to the fetus with an isolated abnormal nuchal skin fold or with one additional abnormality of the heart or a non-cardiovascular organ system. When an abnormal nuchal skin fold is identified, careful evaluation of the fetal cardiovascular system should be made.
DeVore
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Fetal Diagnostic Center of the Genetics Institute, Pasadena, California, USA.
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