Maternal serum screening for Down syndrome in a teaching hospital in Hong Kong.
OBJECTIVE
To study prospectively the use of maternal serum alpha-fetoprotein (AFP) and total beta-human chorionic gonadotropin (hCG) concentrations for screening of Down syndrome in Hong Kong.


METHODS
AFP and total beta-hCG were measured in serum samples from 1638 singleton Chinese pregnancies at 14-22 weeks of gestation, recruited over a twelve-month period. Gestational ages were determined by ultrasonographic parameters measured at the same visit as the test for all cases. The gestational-age-specific and weight-adjusted medians for serum AFP and total beta-hCG were calculated. Risk for fetal Down syndrome (FDS) was derived by mathematical modeling of the medians together with maternal age. Amniocenteses were offered to women with a calculated FDS risk of 1:270 or greater.


RESULTS
The gestational-age-specific and weight-adjusted medians for maternal serum AFP were similar to previous studies while that of total beta-hCG were higher. A total of 101 patients (6.1%) were classified as being high risk for FDS, including 3.4% (48/1394) of those younger than 35 years of age and 21.7% (53/244) of those who were 35 or above. There were 4 cases of Down syndrome, 1 case of Tumer syndrome and 1 of Edward syndrome. Three out of the four cases of Down syndrome were screened positive, corresponding to a detection rate of FDS of 75%. A case of Tumer syndrome was also screened positive. A case of trisomy 18 was found to have very low levels of AFP [0.262 multiple of median (MoM)] and total beta-hCG (0.115 MoM).


CONCLUSIONS
Maternal serum screening using double biochemical markers (AFP and total beta-hCG) in combination with gestational dating by ultrasonography is effective in the detection of fetal Down syndrome and possibly other chromosomal disorders in Chinese pregnant women.
Law
L
L
Department of Chemical Pathology, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, NT, Hong Kong, China. lklaw@mailserv.med.cuhk.edu.hk
Lau
T
T
Fung
T
T
Rogers
M S
MS
Hjelm
M
M
D000328:Adult; D000649:Amniocentesis; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D006723:Hong Kong; D006801:Humans; D007621:Karyotyping; D008875:Middle Aged; D011247:Pregnancy; D011296:Prenatal Diagnosis; D011446:Prospective Studies; D014463:Ultrasonography; D000509:alpha-Fetoproteins / Q000378:metabolism*
D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins