Cytogenetic Analysis in 785 Cases of Midtrimester Amniocentesis Using In Situ Coverslip Culture

Kim, Ji Hyun; Byun, Jae Chun; Shin, Ji Hyun; Song, Geun A; Je, Goo Hwa; Han, Jin Yeong

Abstract

OBJECTIVE
Amniocentesis is the most commonly used invasive method for prenatal diagnosis of genetic disorders. We performed this study to analyze the indications, distributions of maternal age and cytogenetic results of midtrimester amniocentesis.
METHODS
We retrospectively analyzed 785 cases of midtrimester prenatal genetic amniocentesis which were performed in the cytogenetics laboratory using in situ coverslip culture at Dong-A University Hospital from January 1995 to March 2003.
RESULTS
Amniocentesis was practiced mostly from 15 weeks to 20 weeks of gestational ages. Requested indications of amniocentesis were abnormal maternal serum screening (421, 53.7%), advanced maternal age (233, 29.7%) and abnormal ultrasonographic finding (61, 7.8%) in the order of decrease. The overall incidence of chromosome abnormalities was 5.1% (40 cases), and it contains 27 cases (3.4%) of numerical abnormalities and 13 cases (1.7%) of structural abnormalities. Among autosomal abnormalities Down syndrome was most common (13 cases) and followed by Edward syndrome (2 cases). Of the sex chromosomal abnormalities, three cases of Turner syndrome and three cases of Kleinefelter syndrome were found. Chromosomal abnormalities were most frequently noted in the maternal age of 30 to 34 years old (14 cases, 35.0%), 25 to 29 years old (12 cases, 30.0%), followed by 35 to 39 years old (7 cases, 17.5%). The frequency of pseudomosaicism were 5 cases (0.6%).
CONCLUSION
Maternal serum screening, advanced maternal age and antenatal ultrasonographic finding must be important screening methods for amniocentesis which is considered to the most effective diagnostic procecdure for prenatal cytogenetic studies. I conclude that the karyotyping analysis of midtrimester amniocentesis is efficacious method for detection of chromosomal aberration and genetic counselling for parents.