Fetal and Maternal Medicine Review

Research Article

FIRST AND SECOND TRIMESTER SONOGRAPHIC SCREENING FOR FETAL DOWN SYNDROME

JULIA UNTERSCHEIDERa1 c1 and FERGAL D MALONEa1

a1 Royal College of Surgeons in Ireland, Rotunda Hospital, Dublin, Ireland

Screening for Down syndrome is an important part of routine antenatal care and should be made available, if requested, after appropriate counselling including risks and benefits, to all pregnant women, regardless of maternal age. Prenatal screening for fetal Down syndrome and other aneuploidies has advanced significantly since its advent in the 1980s. Historically, women 35 years or older were offered prenatal genetic counselling and the option of a diagnostic test such as chorionic villus sampling or amniocentesis. With this screening approach only 20% to 30% of the fetal Down syndrome population are detected antenatally. Sonographic and maternal biochemical markers are now used in combination to screen for aneuploidies in the first and second trimesters. The most common screening method in the first trimester combines the maternal serum markers HCG and PAPP-A with the sonographic evaluation of fetal nuchal translucency thickness. Newer markers have been proposed to further refine the risk assessment for Down syndrome to maximise detection rates and minimise false positive rates. These newer first trimester markers include sonographic assessment of the fetal nasal bone (NB), the frontomaxillary facial (FMF) angle, ductus venosus (DV) Doppler and tricuspid valve regurgitation (TR).

(Online publication February 15 2011)

Correspondence:

c1 Julia Unterscheider, Royal College of Surgeons in Ireland, Rotunda Hospital, Parnell Square, Dublin 1, Ireland. Email: juliaunterscheider@rcsi.ie