First-trimester screening works well in clinics.(Obstetrics)

RENO, NEV. -- First-trimester aneuploidy screening is practical not just in the context of clinical trials but also in the everyday world of the clinic, according to a poster presented by Sriram C. Perni, M.D., and colleagues at the annual meeting of the Society for Maternal-Fetal Medicine.

Among 2,515 women evaluated at a single institution, trisomy 21 was detected in 91% of 22 pregnancies when the false-positive rate was set to 5% and in 77% of 22 pregnancies when the false-positive rate was set to 1%.

In that same group, trisomy 18 was detected in all eight affected pregnancies, whether the false-positive rate was set to 5% or 1%.

Aneuploidy screening in the first trimester relies on an algorithm incorporating four pieces of data: maternal age, blood levels of pregnancy-associated plasma protein A (PAPP-A), blood levels of free [beta]-human chorionic gonadotrophin (free [beta]-hCG), and ultrasound measurements of fetal nuchal translucency, Dr. Perni said.

A large, multicenter, clinical trial involving 8,514 patients found this algorithm to have a good sensitivity and an acceptable false-positive rate (N. Engl. J. Med. 2003;349:1405-13).

But it remained unclear whether the algorithm would perform as well in the real-world setting of a single institution, reported Dr. Perni and his colleagues at Weill Medical College of Cornell University, New York.

At their clinic, 4,883 pregnant ...