Non-immune hydrops in trisomy-18. Diagnosis by vaginosonography and chorionic villus sampling in the first trimester. Case report

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

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 . or = 2.5 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 > or = 2.5 mm, and 2.8% at a cutoff of > or = 3 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 <2.5 mm in a case of trisomy 18, > or = 2.5 mm in 32 cases and > or = 3 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.