Cytogenetic Analysis for Fetal Chromosomal Abnormalities by Amniocentesis: Review of Over 40,000 Consecutive Cases in a Single Center

Abstract

Background: The aim of this study was to retrospectively investigate the 18-year experience of prenatal diagnosis of fetal karyotype analysis by amniocentesis. Methods: In this study, the authors reviewed the cytogenetic results of 40,208 fetuses with indications for amniocentesis enrolled from December 1998 to December 2015. Cytogenetic analysis of amniotic fluid was performed in all these pregnancies. Eight indications for amniocentesis were included. The detection rate and distribution of abnormal karyotypes were observed in each indication. Results: Among all these samples, abnormal maternal serum screening test was the most common indication for amniocentesis (17,536, 43.67%), followed by advanced maternal age (11,734, 29.18%), abnormal ultrasound findings (5,328, 13.25%), and required by pregnant women (2,557, 6.36%). Chromosomal abnormality was detected in 1,349 (3.36%) samples, 63.01% of the abnormalities were numerical, and 36.99% were structural. The detection rates of abnormal karyotype were 55.60% in one of the couple with chromosomal abnormality, 4.43% in the pregnant women with pathological ultrasound finding, 2.83% in the pregnant women with advanced age, and 2.73% in women with abnormal maternal serum screening tests. Of the fetuses with chromosome aberrations, 680 (50.41%) had trisomy 13, trisomy 18, or trisomy 21, and 138 (10.23%) had sex chromosome disorder. The other 531 abnormal samples included translocation, mosaicism, inversion, deletion, addition, and marker chromosome. Conclusions: Cytogenetic analysis, therefore, remained an effective approach to decrease the birth defects of fetuses with indications for amniocentesis. These results could provide meaningful suggestions for clinical genetic consulting and prenatal diagnosis.