Screening of high-risk pregnancies for down syndrome using quadruple test at a tertiary care center of Nepal

Abstract

Background: Down syndrome (DS) is the most common cause of developmental delay and accounts for 15-30 percent of individuals with intellectual disabilities. No finite published data suggests the prevalence of DS in Nepalese children. There is no definitive protocol from the government or professional bodies regarding screening, though the practice for screening DS is increasing both in the public and private sectors. Objectives: To screen high-risk pregnant women (Age ≥ 30 years) by quadruple biochemical test in the second trimester for Down syndrome and other chromosomal abnormalities. To evaluate the sensitivity and accuracy of the second-trimester screening (quadruple test with genetic sonogram) for trisomy 21 as compared to biochemical testing. Methods: This prospective observational study was conducted in the Department of Clinical Biochemistry in collaboration with the Department of Obstetrics and Gynecology, Institute of Medicine, TUTH, Maharajgunj, Kathmandu, Nepal. Pregnant women at 15-21 weeks of gestation were enrolled. Quadruple test (Alpha-fetoprotein (AFP), beta-human gonadotrophin (hCG), unconjugated estriol (UE3), and Inhibin-A in the laboratory using the technology of Chemiluminescence micro particle two-step immunoassay. Risk estimation using values of hormone levels and the resulting MoM was done using PRISCA 5.0.2.37. Results: 256 high-risk pregnancies were screened for trisomy 21, trisomy 18, and neural tube defects. The mean age of the patient was 33.65 ± 3.71 years. Out of 256 patients, 24 (8%) patients were identified as high risk for trisomy 21, 6 (1.96%) patients for Trisomy 18, and 6 (1.96%) patients for neural tube defects. Multiples of Median (MOM) for AFP in high-risk pregnancy were (1.06 ± 0.57; Sensitivity: 43.8% and specificity: 47.2 %), B-HCG (1.27 ± 0.59; Sensitivity: 87.5% and specificity 71.9%), UE3 (0.86 ± 0.45; Sensitivity: 31.3% and specificity 30.2%) and Inhibin (2.67 ± 1.16; Sensitivity: 81.3% and Specificity: 85.4%) respectively. Conclusion: Second-trimester quadruple test provides an effective screening tool for Down syndrome in the Nepalese population. Quadruple tests combined with sonograms can lower the rates of unnecessary amniocentesis in high-risk populations.