An Evaluation of Prenatal Triple Marker Screening

Cha, Young Joo; Yang, Joo Seok; Chae, Seok Lae; Park, Ae Ja

Abstract

BACKGROUND
Maternal serum triple marker screening has become standard in prenatal care to help identify women at risk for neural tube defects (NTDs), trisomy 21 (Down syndrome) and trisomy 18 (Edwards' syndrome). This study was undertaken to evaluate the results of maternal serum triplemarker screening performed in pregnant women visiting Chung-Ang University Hospital and to assess the effectiveness of prenatal triple-marker screening. METHODS: Alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and unconjugated estriol (uE3) were measured by radioimmunoassay (Amerlex-M 2nd Trimester Kit, Ortho Clinical Diagnostics, Amersham, Aylesbury, UK) in 506 pregnant women visiting Chung-Ang University Hospital. Women at risk for NTDs, trisomy 21 and trisomy 18 were identified using the computer program (HIT Program). Amniocentesis with chromosome analysis was performed in women who had positive screening results. RESULTS: Positive screening results were found in 41 (8.1%) women among 506 pregnant women who had undergone prenatal triple-marker screening between 14 and 22 weeks of gestation. Of these 41 women, 39 (7.7%) had a positive screening results for Down syndrome and 2 (0.4%) for NTDs. Thirty-two women with positive screening results for Down syndrome chose amniocentesis for chromosomal analysis, of which the results showed normal in 28 (87.5%), inv(9) in 3 (9.4%) and 48, XXY, +18 in 1 (3.1%). Although all but one of the fetuses with normal karyotypes and inv(9) were born with normal phenotypes, one pregnancy with 48, XXY, +18 was terminated due to fetal death in-utero. One of 2 pregnancies affected with NTDs was correctly identified, showing meningocele, abdominal wall defect and scoliosis. CONCLUSIONS: Our data confirm chromosome abnormalities or congenital anomalies in about 5% of the pregnancies with positive triple-marker screening results, suggesting an effective prenatal screening test. It has been found that the presence of inv(9) in fetuses might be accompanied by false-positive results for Down syndrome.