Contingent screen 'attractive option' for down detection: decreases need for second-trimester tests.(News)

MIAMI BEACH -- Contingent screening is an attractive option for prenatal detection of trisomy 21, Dr. Fergal Malone said at the annual meeting of the Society for Maternal-Fetal Medicine.

This screening method was analyzed using data from the First and Second Trimester Evaluation of Risk (FASTER) trial, a National Institute of Child Health and Human Development-funded study of pregnant women who underwent screening in both trimesters.

The outcomes of contingent screening were compared with those of two other commonly described screening methods: stepwise sequential screening and integrated screening in more than 32,000 women in the FASTER trial population.

Contingent screening had a detection rate of 93%, with a false-positive rate of 4% in a relative comparison of the three methods for detection of trisomy 21 in the FASTER population. The first-trimester detection rate was 65%, with 2% of patients requiring chorionic villi sampling (CVS), and the second-trimester detection rate was 28%, with another 3% of patients requiring amniocentesis.

Only 22% of patients required additional screening in the second trimester, said Dr. Malone of the Royal College of Surgeons in Dublin.

Stepwise sequential screening had a 95% detection rate with a 5% false-positive rate and a 65% early detection rate. But 98% of patients were required to return for second-trimester screening to achieve these target rates.

Integrated screening had a comparable 92% detection rate, with a false-positive rate of 5%. This method provided no early detection, and required that 100% of patients return for second-trimester screening.