Is nuchal translucency screening associated with different rates of invasive testing in an older obstetric population?

OBJECTIVE

Our objective was to assess the impact of nuchal translucency screening for aneuploidy on chorionic villus sampling and amniocentesis rates in an older obstetric population.

METHODS

Our study population included women >/=35 years old who were delivered at our hospital from January 1, 2000 through December 31, 2002. Records were reviewed to determine whether women underwent nuchal translucency, chorionic villus sampling, and amniocentesis. The chi-squared test for trend was used to evaluate changes in nuchal translucency, chorionic villus sampling, and amniocentesis rates over six 6-month intervals. Maternal characteristics were compared with the use of Mann-Whitney U test and Fisher's exact test.

RESULTS

The 4029 women who met the inclusion criteria had a median age at delivery of 37 years (interquartile range, 36-39 years). The rates of nuchal translucency screening increased from 0% to 41.6% over the study interval. Women who underwent nuchal translucency screening when it was available were older than the women who did not (median age, 37 years [interquartile range, 36-40 years] vs median age, 37 years [interquartile range, 36-39 years]; P=.003). A higher proportion of women who were >/=40 years old underwent nuchal translucency screening when it was available than did women who were 35 to 39 years old (24.9% vs 20.4%; P=.01). Women who underwent nuchal translucency screening were less likely to have chorionic villus sampling compared with women who did not undergo screening (1.9% vs 7.1%; P<.001). Rates of chorionic villus sampling declined over time, although amniocentesis rates remained unchanged. The overall rate of invasive testing declined. Different trends were noted in women who were 35 to 39 years old compared with women who were >/=40 years old.

CONCLUSION

Higher rates of nuchal translucency screening were associated with lower rates of chorionic villus sampling and invasive testing. The addition of first-trimester screening may lead to reduced rates of invasive testing and fewer losses of normal pregnancies.