Prenatal screening tests and prevalence of fetal aneuploidies in a tertiary hospital in Thailand

Abstract

This study evaluated prenatal screening test performance and the prevalence of common aneuploidies at Siriraj Hospital, Thailand. We collected data from screening tests which are first-trimester test, quadruple test, and noninvasive prenatal tests (NIPT) between January 2016 and December 2020. Thirty percent (7,860/25,736) of pregnancies received prenatal screening tests for aneuploidies disorders, and 17.8% underwent prenatal diagnosis tests without screening. The highest percentage of screening tests was first-trimester test (64.5%). The high-risk results were 4% for first-trimester test, 6.6% for quadruple test, and 1.3% for NIPT. The serum screening tests for trisomy 13 and 18 had no true positives; therefore, we could not calculate sensitivity. For the first-trimester test, the sensitivity for trisomy 21 was 71.4% (95% confidence intervals (CI) 30.3-94.9); specificity for trisomy 13 and 18 was 99.9% (95% CI 99.8-99.9); and for trisomy 21 was 96.1% (95% CI 95.6-96.7). For the quadruple test, the specificity for trisomy 18 was 99.6% (95% CI 98.9-99.8), while the sensitivity and specificity for trisomy 21 were 50% (95% CI 26.7-97.3) and 93.9% (95% CI 92.2-95.3), respectively. NIPT had 100% sensitivity and specificity for trisomy 13, 18 and 21, and there were neither false negatives nor false positives. For pregnant women < 35 years, the prevalence of trisomy 13, 18, and 21 per 1,000 births was 0.28 (95% CI 0.12-0.67), 0.28 (95% CI 0.12-0.67), and 0.89 (95% CI 0.54-1.45), respectively. For pregnant women ≥35 years, the prevalence of trisomy 13, 18, and 21 per 1,000 births was 0.26 (95% CI 0.06-1.03), 2.59 (95% CI 1.67-4.01), and 7.25 (95% CI 5.58-9.41), respectively. For all pregnancies, the prevalence of trisomy 13, 18, and 21 per 1,000 births was 0.27 (95% CI 0.13-0.57), 0.97 (95% CI 0.66-1.44), 2.80 (95% CI 2.22-3.52), respectively.