First trimester nuchal translucency: effective routine screening for Down's syndrome.

The objective was to evaluate the effectiveness of 10-14 week nuchal translucency measurement in routine ultrasound screening for Down's syndrome. 11,398 women were scanned at 10-14 weeks of pregnancy for nuchal translucency measurements. The mean maternal age of the screened population was not significantly different from that of the booking population. A 5% screen positive rate was achieved by using a nuchal translucency-derived risk of > or = 1:200. Screening using this nuchal translucency risk would enable the first trimester detection of 16 out of 21 (76%) fetuses with Down's syndrome and 40 out of 49 (81%) aneuploid fetuses. In conclusion, this study demonstrates that first trimester nuchal translucency measurement is an effective method of screening for fetal chromosomal abnormality.