RESUMO
OBJECTIVES: To compare the screening performances of combined screening test risk algorithm for trisomy 18 (T18) using various cutoffs with a multiparameter ultrasound-based method. To compare the general and maternal age (MA)-based screening performances for T18 by means of combined screening and an ultrasound-based method. METHODS: This was a prospective, multicenter study based on a mixed-risk non-selected population of women referred to referral centers for a first-trimester screening. Each subject was offered a choice between either a traditional combined screening (CSG arm) or an ultrasound-based screening (USG arm). General and MA-based screening performances were measured. RESULTS: The study population comprised 10 820 pregnancies as follows: 5132 in the CSG arm, including 28 cases of T18, and 5688 in the USG arm, including 29 cases of T18. In the CSG arm, the detection rate (DR) for T18 at a false-positive rate (FPR) of 3% was 86%, whereas the DR was 100% for the USG arm. MA influenced the T18 screening performance in the CSG arm and reduced the DR in MA ranges <26 years and 31-35 years. This influence was not observed in the USG arm. CONCLUSIONS: Only, a multiparameter ultrasound-based screening method may be considered an effective alternative to combined screening for T18 screening. The technique exhibits high and stable DRs irrespective of MA.