Correlation between nuchal thickness and abnormal karyotype in first trimester fetuses

Abstract

Objective To evaluate the accuracy of ultrasound measurement of nuchal thickness in first trimester fetuses for predicting fetal karyotype. Design A prospective study of the nuchal thickness of fetuses measured during an ultrasound examination in all women undergoing first trimester chorionic villus sampling (CVS). Setting Two major public hospitals and two associated private practices between 7 September 1993 and 6 September 1994. Participants Pregnant women with various indications for CVS (in 82% because of maternal age). Results 1306 women underwent CVS, including 11 with twin pregnancies: 1317 fetuses were tested. Karyotype results were obtained for 1312 fetuses: 41 (3.1%) had an abnormal karyotype, and 20 of these (49%) had a nuchal thickness measurement of 3 mm or more, compared with 44 (3.5%) of the 1271 fetuses with a normal karyotype. Of the 21 fetuses shown to have trisomy 21,12 would have been detected if a nuchal thickness of 3 mm or more had been used as an indicator, giving a sensitivity of 57%. Nuchal thickness measurements of 1 or 2 mm excluded trisomy 21 with a negative predictive value of 99.3%. Fetuses with moderate nuchal thickening, normal karyotype and no other problems noted on the initial ultrasound scan had neonatal outcomes similar to those in the general obstetric population. Conclusion Nuchal thickening in the first trimester (10 weeks on) of pregnancy in a high risk population is a powerful indicator of increased risk of aneuploidy.

Optimising the timing for nuchal translucency measurement

“…In the 5835 pregnancies with a CRL between 45 and 84 mm we were unable to take a measurement in only 16 (0.3%) cases with a low rate of transvaginal scanning. The scanning was performed by a number of individuals in a busy public hospital, confirming that NT-based screening in a public hospital is feasible to perform, quite unlike previous reports where the failure rates were unacceptably high Bewley et al, 1995;Kornmann et al, 1996;Haddow et al, 1998;Hewitt et al, 1996 andScott et al, 1996) but similar to other large series (Pandya et al, 1995;Theodoropoulos et al, 1998). It is likely that the differences between these former studies and our study (together with the Cherstey group and Greek multicentre studies) is that the NT measurement was performed as part of a Down Syndrome screening programme and used to derive risks upon which management was based rather than simply measuring the NT for research purposes.…”

Screening for Down's syndrome by fetal nuchal translucency measurement in a high‐risk population

“…Since the introduction of screening by nuchal translucency measurement, numerous prospective studies have been published [2][3][4][5][6][7][8][9][10][11][12][13][14] . With a fixed cut-off point used as normal, the detection rate of trisomy 21 has been reported to range from 29% 11 to 85% 6 , with false-positive rates ranging from 0.9% 8 to 6.0% 7 .…”

“…The measurement of nuchal translucency in these cases could therefore be superfluous. In some of the above-mentioned studies, these cases were included 3,4,9,12 . Although Comas and colleagues 5 reported that they had excluded cases of cystic hygroma, most reports do not state whether fetuses with structural anomalies have been excluded or not.…”

“…Taking these methodological problems into account, the results of this study can at best be compared to other prospective screening studies in women undergoing fetal karyotyping [2][3][4]10,[12][13][14] . Our detection rate of 69% for trisomy 21 fetuses compares favorably with detection rates of 30% 4,10 , 44% 13 , 53% 14 , 54% 2 and 57% 12 , but is worse than the 84% detection rate reported by Nicolaides and colleagues 3 .…”

Nuchal translucency, ductus venosus and congenital heart disease: an important association – a cautious analysis

“…Measurement of nuchal translucency in the first trimester of pregnancy has also drawn enormous attention in recent years as a non-invasive screening method for chromosomal abnormalities [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] . In second-trimester fetuses (14-23 weeks), DeVore and Alfi found a significant association between abnormal nuchal fold and chromosomal and cardiac defects 23 .…”