Cytogenetic Analysis in 651 Cases of Amniocentesis

Kim, Young Jae

Abstract

BACKGROUND: The purpose of this study was to analyze the cytogenetic results of amniocentesis in terms of patients' ages and indications. It was further intended to examine the temporal trend in amniocentesis indications for cytogenetic analysis.
METHODS
A total of 651 cases of amniocentesis were examined at Masan Samsung Hospital dur-ing the period 1996 to 2001 and were used to analyze the age distribution, indications, and chromo-somal results in relationship to maternal age and with the indication for amniocentesis.
RESULTS
The overall rate for chromosomal abnormalities was 3.8% (25 out of 651 cases). In addi-tion, the 25-29 age group fell into the most common age distribution group with 261 from 651 amnio-centesis cases (40.1%). It turned out that the abnormal triple test for alpha-fetoprotein (AFP), the human chorionic gonadotropin (hCG), and the unconjugated estriol (nE3 ) were the most common indications for amniocentesis (51.4%), and 3.9% (13 out of 335 cases) showed chromosomal abnormalities. Among 25 cases of chromosomal abnormalities, 18 cases were numerical and 7 cases were struc-tural abnormalities. In 18 cases of numerical abnormalities, there were 12 Down syndrome cases, 4 Edwards syndrome cases, 1 Patau syndrome case and 1 Turner syndrome case. In 7 cases of struc-tural abnormalities, there were 6 cases of reciprocal translocation and 1 case of Robertsonian translo-cation.
CONCLUSIONS
A primary indication for cytogenetic analysis in mid-trimester amniocentesis appeared as an abnormal triple test. Although such triple tests were effective enough in detecting chromoso-mal abnormalities in fetuses, it increased unnecessary amniocentesis. It is proposed that a new technique for non-invasive prenatal diagnosis for chromosomal abnormalities with a sufficient detection rate and a low false positive rate (such as analysis of fetal nucleated red blood cells from maternal blood) should be introduced.