Integrace antenatálního screeninguDownova syndromu v I.a II.trimestru(návrh screeningového protokolu)

Integration of Antenatal Down SyndromeScreening at 1 st and 2 nd Trimester (Proposalof Screening Protocol)

Objective:
Proposal of antenatal Down syndrome screening protocol using integration of first andsecond trimester results.Design:Review.Setting:Antenatal screening centre GENNET,Prague.Methods:Search of relevant articles,software analysis and pilot implementation.Results:Screening of Down syndrome (DS)is divided into two phases:at first phase combined DSrisk is calculated using pregnancy plasma protein –A (PAPP-A)at 9 th –11 th gestational week andultrasound fetal nuchal translucency (NT)at 11 th –13 th week with risk cut-off 1/100 (about 2 percent of screened).Positive mothers are counselled immediately after NT measurement:Firstphase negative mothers continue to second phase where PAPP-A and NT values are integratedwith second trimester screening results.Protocol is supported with special software (Obstetrician ’s Screening Guide-OSG).Conclusion:At proposed protocol the information on significant first trimester DS risk is notwithheld to second trimester and mother can choose early prenatal diagnosis.Expected detectionrate is near 90 per cent at 5 per cent false positive rate.

Key words:
integrated antenatal screening,Down ’s syndrome,screening protocol