Cytogenetic Analysis in 3,503 Cases of Midtrimester Amniocentesis: CUMC Experience (II)

Park, In Yang; Shin, Jong Chul; Kim, Seok Chan; Ahn, Hyun Young; Moon, Hee Bong; Park, Cheol Hoon; Lee, Hee Joong; Lee, Young; Rha, Chong Gu; Kim, Soo Pyung

Abstract

OBJECTIVE
To analyze chromosomal abnormalities according to patient's age and indications of patients in midtrimester amniocentesis for prenatal genetic diagnosis.
METHODS
We retrospectively analyzed 3,503 cases of midtrimester prenatal genetic amniocentesis cases which were done in the cytogenetic laboratory at Kangnam St. Mary's Hospital, Catholic University Medical College.
RESULTS
In 3,503 cases, the most common maternal and gestational age distributions were 35 to 39 years old and 17 to 17 week 6 days (32.2% and 21.5%, respectively). Abnormal maternal serum markers was the most common indication for amniocentesis (46.4%), and followed by advanced maternal age (40.3%) and abnormal ultrasonographic findings (3.2%). The overall incidence of chromosomal abnormalities was 180 cases (5.1%), of which numerical abnormalities and structural abnormalities were 78 cases (2.2%) and 102 cases (2.9%), respectively. Among the autosomal abnormalities, Down syndrome was most common (33 cases, 0.9%), and followed by Edward syndrome (17 cases, 0.5%). Among the sex chromosomal abnormalities, 45,X was the most common (6 cases, 0.2%). Chromosomal abnormalities were most frequently noted in the maternal age 18-19 years old (14.3%), 40 to 44 years old (7.0%), 25 to 29 years old (6.1%), 30 to 34 years old (5.2%), and followed by 20 to 24 years old (4.1%). On the other hand, chromosomal abnormalities were most frequently noted in abnormal ultrasonographic findings (12.4%), previous history of aneuploidy (8.3%), and followed by family history of aneuploidy (7.0%).
CONCLUSION
This study suggested that although advanced maternal age is still important indication in midtrimester amniocentesis for prenatal diagnosis, abnormal maternal serum markers and ultrasonographic findings might be also important as indications. Therefore, they should be considered in prenatal genetic counseling.