RESUMO
OBJECTIVE: To compare the usefulness of prenatal screening tests for chromosomal abnormalities by analyzing the cytogenetic results of midtrimester amniocentesis METHODS: We reviewed a total of 1264 cases of midtrimester prenatal genetic amniocentesis performed from February 1997 to September 2003, of which accorded to indications of cytogenetic studies. Cytogenetic results were analyzed with the distribution of maternal age, indications of amniocentesis. RESULTS: The most common age of total subjects was in between 35-39 years (37.1%). The indications of amniocentesis were abnormal maternal serum marker (60.0%), advanced maternal age (34.8%), abnormal ultrasonographic findings (3.2%), in order. The overall incidence of chromosomal aberration was 3.9% (49/1264). No significant difference was found between the mean maternal age with and without abnormal fetal karyotype. According to indications, there was 12.5% (5/49) of chromosomal abnormalities in abnormal sonographic finding group, 5.2% (36/688) in abnormal maternal serum screening group and 2.4% (12/498) in advanced maternal age group. There was statistical significance (P=0.004) only in abnormal ultrasonographic finding group. CONCLUSION: Ultrasonography was become to be more important due to development of high resolution ultrasonography, skillful technique and awareness of sonographic markers. Ultrasonographic abnormality could be the most predictive marker for abnormal fetal karyotypes.