NT of 4 mm or more warrants chorionic villus sampling.(News)(nuchal translucency)

MIAMI BEACH -- A nuchal translucency measurement of at least 4 mm identified during prenatal ultrasound screening for aneuploidy warrants immediate consideration of chorionic villus sampling, Dr. Fergal Malone reported at the annual meeting of the Society for Maternal-Fetal Medicine.

In such cases, there is no added benefit in performing serum screening or in using the nuchal translucency (NT) value for developing a risk assessment algorithm because a measurement of at least 4 mm is indicative of extremely high aneuploidy risk, said Dr. Malone, professor and chair of the department of obstetrics and gynecology at the Royal College of Surgeons in Ireland and Rotunda Hospital, Dublin.

The finding is based on an analysis of data from more than 36,000 of the women who participated in the National Institute of Child Health and Human Development-funded First and Second Trimester Evaluation of Risk (FASTER) trial.

Data used in this analysis were from women who underwent both NT measurement and serum testing. Of the 32 FASTER participants who had a simple NT measurement of at least 4 mm, 1 in 3 had aneuploidy and 1 in 11 had fetal demise. The lowest final first-trimester risk quoted for any of these patients based on NT measurement alone was 1 in 8, and for those with aneuploidy, the lowest risk quoted was 7 in 8. No patient in this group had a final risk assessment reduced to a more reassuring level (1 in 100 or less) by the addition of serum markers, Dr. Malone said.

Of the 128 patients ...