Changes in the utilization of prenatal diagnosis.

OBJECTIVE

The impact of prenatal screening for Down syndrome has largely been assessed under the assumption that screening protocols and policies are fully used. To measure the overall effectiveness in actual clinical practice, we analyzed the tests performed by a single cytogenetics laboratory.

METHODS

We reviewed all amniotic fluid and chorionic villus samples (CVS) processed by the University of Connecticut Health Center's cytogenetics laboratory for the years 1991 to 2002. We evaluated trends in the use of prenatal testing, referral indications, and the numbers of cytogenetic abnormalities identified.

RESULTS

The number of women receiving amniocentesis or CVS declined more than 50% from 1,988 in 1991 to 933 in 2002 (P <.001), despite an increase in the number of women of advanced maternal age in the population served. There was a 68% decline in the number of women who underwent invasive prenatal testing solely on the basis of their age (1,314 in 1991 to 423 in 2002, P <.001). The number of Down syndrome fetuses detected prenatally increased from 20 to 31 (P =.08), representing approximately one half of the affected pregnancies present in the population served. Between 1991 and 2002, the proportion of antenatal cytogenetic tests with a significant chromosomal abnormality increased from 1 in 43 (2.3%) to 1 in 14 (7.0%; P <.001).

CONCLUSION

Advances in maternal serum screening and second-trimester ultrasonography have resulted in more judicious use of amniocentesis and chorionic villus sampling.

LEVEL OF EVIDENCE

II-2