Acceptability of serum screening as an alternative to cytogenetic diagnosis of Down syndrome among women 35 years or older in Hong Kong

The addition of second trimester serum markers to maternal age increases th e efficacy of screening for Down syndrome by maternal age alone. Among wome n aged 35 years or older, serum screening makes a large proportion of amnio centesis unnecessary. However, there are ethical and medicolegal concerns a bout serum screening in 'old' women, largely because some of the pregnancie s affected by Down syndrome and other chromosomal abnormalities may not be detected. We investigated the acceptability of serum screening in women age d 35 years or older when it was offered as an alternative to prenatal cytog enetic diagnosis after detailed counselling. Women referred for prenatal di agnosis of Down syndrome because of advanced maternal age were given the op tions of cytogenetic diagnosis by chorionic villus sampling (CVS) or amnioc entesis. As an alternative, they could choose to undergo second trimester s erum human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) screen ing first before deciding on whether to undergo amniocentesis. Between Janu ary 1997 and October 1999, 3419 subjects were recruited. 1807 women (52.9%) chose to undergo serum screening, 1516 women (44.3%) chose to have amnioce ntesis and 96 women chose to have CVS (2.8%). The proportion of women who c hose serum screening rose steadily from 38.8% in the year of 1997 to 63.4% in 1999. Significantly fewer Chinese women chose serum screening than non-C hinese. The decision as to whether to undergo an invasive diagnostic proced ure or to be content with the relatively safer but less accurate screening test varies, being affected by the women's background and culture. Copyrigh t (C) 2000 John Wiley & Sons, Ltd.