The importance of screening and prenatal diagnosis in the identification of the numerical chromosomal abnormalities.

BACKGROUND AND AIMS The obstetric care of a pregnancy, as it is practiced today, includes non-invasive screening approaches as well as invasive procedures for the definitive prenatal diagnosis of fetal disorders correlations between indications for prenatal cytogenetic diagnosis and results of the chromosomal analysis made upon fetal cells. The aim of our study was to evaluate the correlations between the screening test results and results of chromosomal analysis on fetal cells. METHODS Amniotic fluid samples from 1159 pregnant women were studied with the rapid FISH method and the cytogenetic analysis (karyotype). The results from both methods were compared. RESULTS The indications to perform prenatal cytogenetic diagnosis for numerical chromosomal abnormalities were: abnormal results of double or triple test, advanced maternal age, fetal abnormality detected through ultrasound examination, and positive family history for chromosomal anomalies. In our study we identified 30 cases with abnormal numeric chromosomes (18 cases of trisomy 21, 4 cases of trisomy 18, 3 cases of trisomy X, 1 case of monosomy, 2 cases of trisomy XYY, 1 case of trisomy XXY and 1 case of triploidy). CONCLUSIONS This report confirms the importance of screening and the cytogenetic diagnosis in the identification of the numerical chromosomal abnormalities.