Cytogenetic and clinical analysis of midtrimester amniocentesis

Choi, Suk Joo; Kim, Woo Sun; Kim, Ji Un; Lee, Eun Sil; Cho, Eun Hae; Kim, Sun Hee; Roh, Cheong Rae; Kim, Jong Hwa

Abstract

OBJECTIVE
To analyze the clinical features and cytogenetic results of midtrimester amniocentesis.
METHODS
We reviewed retrospectively medical records of 1,622 women who received amniocentesis from 1998 to 2003. The maternal age and gestational age at amniocentesis, indications, cytogenetic results and complications of amniocentesis were analyzed.
RESULTS
A total of 1,653 cases of amniocentesis were performed in 1,590 singleton pregnancies and 32 twin pregnancies. The mean age at amniocentesis of singleton pregnancies was 33.5 +/- 4.3 years, and the most common age group was from 35 to 39 (38.6%) and those of twin pregnancies were 33.1 +/- 3.6 years and from 30 to 34 (50.0%), respectively. Majority of the cases (78.9%) were performed between 16th and 19th weeks of gestation. Advanced maternal age was the most common indication of amniocentesis (46.2%), followed by abnormal serum screening test (32.9%) and abnormal ultrasonographic findings (10.0%). Abnormal fetal karyotype results were identified in 34 cases (2.1%). 24 cases were numerical aberration and the other 10 cases were structural aberration. Trisomy 21 was the most common abnormal karyotype (23.5%). There was no abnormal karyotype results from 63 amniocentesis performed in twin pregnancies. Positive predictive value of abnormal ultrasonographic finding, advanced maternal age and abnormal serum screening test were 3.0%, 2.5%, 1.5% respectively. The procedure-related fetal death occurred in 7/1,353 (0.51%).
CONCLUSION
Among the several indications of midtrimester amniocentesis, advanced maternal age was the most common indication, whereas abnormal ultrasonographic finding had the most powerful predictive value for abnormal fetal karyotype.