Prospective study of the feasibility and effectiveness of a second-trimester quadruple test for Down syndrome in Thailand

Objective: To evaluate the feasibility and effectiveness of a quadruple test for Down syndrome in the second trimester of pregnancy in clinical settings in Thailand. Methods: From October 2015 to September 2016, a prospective study was undertaken in 19 hospitals in Songkhla province, Thailand. Women with a singleton pregnancy of 14-18 weeks were enrolled and underwent the quadruple test. The risk cutoff value was set at 1: 250. All women with a positive test (risk >= 1: 250) were offered amniocentesis. Women were followed up until delivery. Results: Among 2375 women, 206 (8.7%) had a positive quadruple test; 98 (47.6%) of these women voluntarily underwent amniocentesis. Overall, seven pregnancies were complicated with chromosomal abnormalities (2.9 cases in 1000), including four cases of Down syndrome (1.7 in 1000) and three of other abnormalities. The detection, false-positive, and accuracy rates of the quadruple test for Down syndrome were 75.0%, 8.6%, and 91.4%, respectively. Conclusion: The quadruple test was found to be a feasible and efficient method for screening for Down syndrome in the second trimester of pregnancy in a Thai clinical setting. The test should be performed for pregnant women before an invasive test for Down syndrome.