Experience on Triple Markers Serum Screening for Down’s Syndrome Fetus in Hat Yai, Regional Hospital
Surachai Lamlertkittikul MD*, Verapol Chandeying MD**
Affiliation : * Department of Obstetrics and Gynecology, Hat Yai Regional Hospital, Hat Yai, Songkhla ** Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkhla University, Hat Yai, Songkhla
Objectives : To summarize the experience and evaluate the performance of the Hat Yai maternal serum screen-
ing (MSS) program.
Setting : The Hat Yai MSS program between 16 February 2003 and 11 March 2004.
Materials and Methods : The uptake of screening was 999 in 1,040 women (96.0%), between 14 to 20 weeks of
gestation with the triple markers: Alpha-fetoprotein (AFP), human Chorionic Gonadotropin (hCG), and
unconjugated Estriol (uE3) by Immulite chemiluminescent immunoassay system, Diagnostic Product Corpo-
ration (DPC). The risk cut-off for Down’s syndrome is one in 250 or greater, based on software for prenatal
Down’s syndrome risk calculation, by Prisca 3.5 DPC.
Results : There were 119 in 999 cases (11.9%) of the triple test positive. Amniocentesis had been performed on
voluntary basis, and the uptake rate of amniocentesis following a positive Down’s syndrome screening was 104
in 119 cases (87.3%). Based on clinical diagnosis of Down’s syndrome in the newborns of non-amniocentesis
mothers, assuming that normal looking babies were not Down’s syndrome, the sensitivity (SENS), specificity
(SPEC), positive predictive value (PPV), and negative predictive value (NPV) of all chromosomal abnormalities
were 85.7%, 88.6%, 5.0%, and 99.8% respectively. The false positive rate was 113 in 992 cases (11.4%).
Whereas, the SENS, SPEC, PPV, and NPV of Down’s syndrome were 100%, 88.4%, 3.4%, and 100% respec-
tively. The false positive rate was 115 in 995 cases (11.6%). The mean level, median level, and multiple of
median (MoM) of triple markers were demonstrated.
Conclusion : The Down’s syndrome screening is a systematic application of a test to identify subjects at
increased risk of a specific disorder, of course it is not diagnostic, but to benefit making decision regarding further
amniocentesis. The sensitivity of Prisca 3.5 software was satisfactory but false positive rate was remarkably
high. It needs further standardization with adjusted MoM values.
Keywords : Triple test, Second trimester, Down’s syndrome, Alpha-fetoprotein, Human chorionic gonadotropin, Unconjugated estriol
