Total hCG versus free beta-hCG combined with alpha-fetoprotein for Down syndrome screening in Taiwan.
OBJECTIVE
The purpose of this study was to compare the effectiveness between total human chorionic gonadotropin (hCG) and free beta-hCG in two-marker Down syndrome screening programs during the second trimester in a Taiwanese population.


METHODS
From a multicenter collaborative study, we investigated the second-trimester maternal serum levels of total hCG from 67 data, free beta-hCG from 72 and alpha-fetoprotein (AFP) from 96 obtained from Taiwanese pregnant women carrying fetuses with Down syndrome.


RESULTS
High total hCG and free beta-hCG, as well as low AFP levels, were found with median values of 2.06, 2.49 and 0.77 multiples of the median (MoM), respectively. At a 5% false-positive rate, total hCG and free beta-hCG could detect 31% and 43% of Down syndrome pregnancies, respectively, whilst AFP alone could detect only 15% of affected cases. When combined with maternal age-specific risk, total hCG could achieve a 52% detection rate, free beta-hCG a 54% and AFP a 39%. Combined total hCG and AFP achieved a detection rate of 55%, and combined free beta-hCG and AFP achieved a rate of 60%.


CONCLUSIONS
The measurement of free beta-hCG is more beneficial than total hCG in serum screening for Down syndrome during the second trimester of pregnancy.
Hsieh
Tsang-Tang
TT
Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Taipei, Taiwan.
Hsu
Jenn-Jeih
JJ
Cheng
Po-Jen
PJ
Lee
Chien-Nan
CN
Jou
Hei-Jen
HJ
Chen
Chih-Ping
CP
D000328:Adult; D044466:Asian People; D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D013624:Taiwan; D000509:alpha-Fetoproteins / Q000378:metabolism
C097353:AFP protein, human; D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins