Four years experience of first-trimester nuchal translucency screening for fetal aneuploidies with increasing regional availability

Abstract

Background. A prospective screening study was carried out at the regional genetic and perinatal center in South Hungary in order to determine the efficiency of first-trimester nuchal translucency screening for fetal aneuploidies, following augmentation of the availability of nuchal translucency screening in the region by the inclusion of newly-trained hospital sonographers. Methods. Nuchal translucency thickness was measured by transvaginal sonography in 7,044 women with singleton or multiple pregnancies at weeks 10-12. Fetal karyotyping was performed when the nuchal translucency was Ø2.5 mm, and in women with fetuses at high cytogenetic risk. Results. Follow-up was performed in 6,841 of the 7,044 screened women. An abnormal karyotype was found in 33 cases (0.48%). The level of increased nuchal translucency was 4.5% at a cutoff of Ø2.5 mm, and 2.8% at a cutoff of Ø3 mm. Seventeen cases of trisomy 21, eight of trisomy 18, four of trisomy 13, one of 45,X, one of triploidy and two cases with other chromosomal abnormalities were detected. In the 33 fetuses with a chromosomal abnormality, the nuchal translucency thickness was Ͻ2.5 mm in a case of trisomy 18, Ø2.5 mm in 32 cases and Ø3 mm in 28 cases. With cutoffs of 2.5 mm and 3 mm, the sensitivity was 96.97% and 84.85%, respectively. Conclusions. Application of a nuchal translucency thickness cutoff of 2.5 mm is highly efficient for the screening of fetal aneuploidies at 10-12 weeks. This efficiency can be maintained by increasing the regional availability of nuchal translucency screening through the inclusion of newly-trained hospital sonographers.

One‐stop clinic for assessment of risk for trisomy 21 at 11–14 weeks: a prospective study of 15 030 pregnancies

“…is similar to the results of the previous 14 prospective studies examining the implementation of fetal NT measurement in screening for chromosomal defects 2,[12][13][14][15][16][17][18][19][20][21][22][23][24] . Thus, the combined results on a total of 174 473 pregnancies, including 728 with trisomy 21, demonstrated a detection rate of 77% for a false-positive rate of 4.7%.…”

One-stop clinic for assessment of risk of chromosomal defects at 12 weeks of gestation

“…There are 14 prospective studies examining the implementation of nuchal translucency measurement in screening for chromosomal defects (Table 1) [14][15][16][17][18][19][20][21][22][23][24][25][26][27] . Although different cut-offs were used for identifying the screenpositive group, with consequent differences in the false-positive rate and sensitivity, they all reported high detection rates.…”

Screening for chromosomal defects

“…In the 1990s it was realized that this excess skin could be visualized by ultrasonography as increased NT in the third month of intrauterine life6. Fetal NT at the 11–14‐week scan has been combined with maternal age to provide an effective method of screening for trisomy 21; for an invasive testing rate of 5%, about 75% of trisomic pregnancies can be identified7–20. When maternal serum free‐β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) at 11–14 weeks are also taken into account, the detection rate of chromosomal defects is about 90%21–25.…”

“…There are 14 prospective studies examining the implementation of NT measurement in screening for trisomy 21 (Table 4)7–20. Although different cut‐offs were used for identifying the screen‐positive group, with consequent differences in the false‐positive and detection rates, all the studies reported high detection rates.…”