The utility of nuchal translucency ultrasound in identifying rare chromosomal abnormalities not detectable by cell‐free DNA screening

Abstract

Objective:To evaluate the utility of nuchal translucency (NT) screening in the detection of rare chromosomal aneuploidies in the setting of cell-free DNA (cfDNA). Methods: A retrospective cohort study of pregnancies screened through the California Prenatal Screening Program between March 2009 and December 2012. Karyotype analysis was the primary method of chromosomal evaluation during the study period and abnormal chromosomal karyotype results were classified by whether the abnormality would be detectable by cfDNA (nonmosaic trisomy 13, 18, 21 or sexchromosomal aneuploidy [SCA]). For those rare aneuploidies detectable by karyotype but not cfDNA, the number of cases that had an increased NT and the detection rate and positive predictive value (PPV) of increased NT for rare aneuploidies were determined. Results: A total of 452 901 pregnant women had screening. There were 2572 chromosomally abnormal fetuses, of which 1922 (74.7%) had a common aneuploidy detectable by cfDNA, leaving 450 979 without T13, 18, 21. Of these, 4181 (0.93%) had an NT ≥3.0 mm. There were 649 rare aneuploidies not detectable by cfDNA.Of these, 108 (16.6%) had an NT ≥3.0 mm. The PPV of an NT ≥3.0 mm for rare aneuploidies was 2.6%. In all, 4176 fetuses need to be screened with NT to detect a rare aneuploidy. Conclusions:The addition of NT to cfDNA screening would detect 16.6% of rare aneuploidies. Increased NT has a low PPV for rare aneuploidies and a large number of women would need NT screening to detect each affected fetus.

The clinical usefulness of cell-free DNA screening in pregnancies with a nuchal translucency between 95th and 99th percentile

“…As a result, women with higher NT were more likely to prefer IT, but old age ([? ]35 years) did not affect the preference for IT [12]. In our cohort, there was no difference in the choice of first-tier test according to the NT value (P= 0.084).…”

“…In this study, chromosomal abnormalities were 5.6% and T21 accounted for 80% of chromosomal abnormalities. Berger et al reported that rare aneuploidies undetectable by cfDNA screening were found in 0.8% of pregnancies with NT between 3mm and 3.5mm [12]. A large cohort study showed chromosomal abnormalities undetected by cfDNA screening but detected by classic karyotyping in 0.6% of fetuses with NT between 95 th and 99 th percentile [21].…”

Importancia clínica de la evaluación ecográfica de la translucencia nucal fetal

“…Durante el primer trimestre del embarazo, los estudios sobre detección del SdD han demostrado que la evaluación de la TN fetal combinada con las pruebas bioquímicas, con tasa de falsos positivos de 5 %, tiene un porcentaje de detección de 78,7 % (intervalo de confianza del 95 %, 66,3 % -88,1 %) (9). Un estudio Entre las 11-14 semanas de gestación, la regurgitación tricúspidea ocurre aproximadamente en 5 % de los fetos normales, mientras que 70 % de los fetos con SdD presentan esta alteración (34,35).…”

How much can AI see in early pregnancy: A multi-center study of fetus head characterization in week 10-14 in ultrasound using deep learning

“…In particular, the measurement of nuchal translucency (NT), a sonolucent area in the posterior fetal neck can be used to evaluate the risk for chromosome defects such as Down syndrome [3][4][5][6] , affecting ~1 per 650-1000 newborns worldwide 7,8 . Moreover, an increased thickness of NT under ultrasonography in late rst trimester is an established indicator of various structural abnormalities, congenital disease like cardiac defects and a number of other genetic syndromes [9][10][11][12][13] . The loss of nasal bone in fetus head scan is also associated with a few chromosome diseases including Down Syndrome [14][15][16] .…”