Cytogenetic and Clinical Analysis in 3,537 Cases of Midtrimester Amniocentesis

Jang, Sung Kyoo; Choi, Ook Hwan

Abstract

OBJECTIVE
To analyze the incidence of chromosomal abnormalities according to age and indications in midtrimester amniocentesis performed for prenatal genetic diagnosis.
METHODS
We retrospectively analyzed the results of 3,537 cases of midtrimester prenatal genetic amniocentesis which were performed from 1994 to June 2006 in the cytogenetic laboratory at Pusan National University Hospital.
RESULTS
Of the 3,537 midtrimester amniocentesis cases, the most common maternal age group was 25~29 years old (32.8%), followed by 30-34 years old (32.1%) and 35~39 years old (24.3%). The indications for amniocentesis were abnormal triple test (42.6%), advanced maternal age (31.8%), family history of chromosomal abnormality (7.0%), in the respective order. The overall incidence of chromosomal abnormalities was 5.0%, of which numerical abnormalities and structural abnormalities were 2.4% and 2.6%, respectively. Chromosomal abnormalities were most frequently found in the maternal age over 45 (16.7%), followed by 40~44 years old (6.3%) and 25~29 years old (5.6%). According to the indications of amniocentesis, chromosomal abnormalities were found in patients with habitual abortion (21.2%), previous history of chromosomal abnormality (14.3%), abnormal finding on ultrasonography (11.5%) and advanced maternal age (5.7%), in the respective order.
CONCLUSION
In this study, in addition to although abnormal triple test and advanced maternal age as important indications of midtrimester amniocentesis for prenatal diagnosis, other indications such as habitual abortion, previous history of chromosomal abnormality and abnormal finding on ultrasonography should be considered important as indications of midtrimester amniocentesis.