2ND-TRIMESTER MATERNAL SERUM ALPHA-FETOPROTEIN AND HUMAN CHORIONIC-GONADOTROPIN SCREENING FOR DOWNS-SYNDROME IN HONG-KONG

Second-trimester maternal serum screening for fetal Down's syndrome is well established in many Western countries. Its usefulness and accept ability is unknown in the Asian countries. Between June 1994 and Decem ber 1996, we offered second-trimester serum AFP and hCG screening to p regnant women in Hong Kong who were less than 35 years old and without other risk factors for chromosomal abnormalities. Each woman was assi gned a risk of having a Down's syndrome term pregnancy by using a comp uter software program that took into account her age, weight, AFP and hCG MOMs. All those with a risk of one in 250 or greater were designat ed screen-positive, subject to the revision of gestation by ultrasound examination. 9177 women with singleton pregnancies (93 per cent were Chinese) were screened. The uptake of screening was 75 per cent. 281 w omen (three per cent) were initially classified to be screen-positive, After revision of the gestation by ultrasound examination, 183 women (two per cent) were 'true' screen-positive and 164 (90 per cent) accep ted the offer of amniocentesis. Eight of these pregnancies were affect ed by Down's syndrome and all the women elected pregnancy termination. The odds of being affected, given a positive screening result, were o ne in 23. Six Down's syndrome pregnancies were missed by the screening programme. The detection rate was 57 per cent. The study showed that second-trimester serum screening for fetal Down's syndrome was feasibl e and acceptable in the Hong Kong population. (C) 1998 John Wiley & So ns, Ltd.