Online Journal
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Journal of Medical Ultrasonics

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2016 - Vol.43

Vol.43 No.Supplement

特別プログラム 産婦人科
パネルディスカッション 産婦人科 Joint(JSUM・AFSUMB Joint Session)(English) 妊娠初期におけるスクリーニングと診断



Significance and limitation of nuchal translucency and usefulness of additional first trimester screening markers

中村 靖



Director, FMC Tokyo Clinic

キーワード :

Nuchal translucency(NT)is a primary marker of the first trimester screening(FTS)for fetal aneuploidy. However, as FTS is not commonly practiced in Japan, majority of obstetricians do not know how to evaluate fetal aneuploidy risks by using NT with other ultrasound and serum markers, and are not aware of the significance and limitation of NT measurement. In this presentation, we will describe the fetal outcomes after FTS performed at our clinic, and discuss the limitation of NT and usefulness of other markers.
【Material and Methods】
We conducted a retrospective review of 2960 pregnant women who underwent FTS at our clinic between September 2013 and December 2015. We used the UK-FMF aneuploidy risk calculation system by using NT with other ultrasound markers(fetal heart rate, nasal bone, tricuspid regurgitation, and ductus venosus flow)with or without serum markers(freeβ-hCG and PAPP-A). Cases were stratified according to NT thickening, and outcomes were compared.
Of the 2960 cases, 357(12.1%)had above 95 percentile of NT thickness. Among them, 122 underwent invasive tests, and chromosomal abnormalities were found in 38/122(31.1%)cases; twenty-one trisomy 21,six trisomy 18(including mosaicism), three trisomy 13,four 45,X, one trisomy 9 mosaicism, one partial trisomy 15,one partial deletion of chromosome 13,and one 47,XXY. There were significant number of cases, which NT were above 95 percentile, but calculated aneuploidy risks were low when other ultrasound and serum markers were added, and no chromosomal abnormalities has been found so far with these people. On the other hand, there were five aneuploidy cases found after invasive tests, where their NT measurements were normal, but their calculated risks were high due to other markers, or with other specific findings, such as megacystis, holoprosencephaly, and omphalocele. There were also some cases with thick NT, and non-chromosomal birth defects were found by detailed sonogram, such as asplenia, skeletal dysplasia, and a male fetus with incontinentia pigmenti suggested by family history and later confirmed by genetic testing.
According to our data, only 31.1%had chromosomal abnormalities when their fetuses showed thick NT. Therefore, obstetricians should be careful when they incidentally find thick NT, and utilization of other ultrasound and serum markers should be considered to decrease the false positive rate. Furthermore, the use of other ultrasound and serum markers may decrease the false negative rate. Overall, to have more accurate aneuploidy risk calculation in the FTS, it would be recommended to utilize not only NT measurement but also other ultrasound and serum markers.