en Gynecology & Obstetrics Gynecology & Obstetrics Original Research Original Research Early identification of fetuses with chromosomal abnormalities enables health care providers to form an appropriate management plan for each patient. The main objective of this study was to determine the role of ultrasonography in screening and identifying fetuses at risk for chromosomal abnormalities. A retrospective review of 6480 patients from the Obstetrics and Gynecology ward of Firouzgar hospital in Tehran was undertaken. Computer databases of patients were correlated to compare the results of the fetal ultrasonographic examination with the cytogenetic results from amniocentesis. Univariate and multivariate analyses were used to determine the best correlations between ultrasonography findings and chromosomal abnormalities. Thirty-seven chromosomal abnormalities were found in 6480 fetuses (0.57%). Down syndrome was the most common finding with trisomy 18 and 13 being the next two most common abnormal findings. Multivariate analysis showed significant correlations between anomalies of the central nervous system, heart, face and neck, and extremities and increased nuchal fold, increased bowel echogenicity, abnormal biparietal diameter to femur ratio and the presence of chromosomal abnormalities (p value<O.OO l). Analysis of data indicated that the presence of any kind of ultrasonographic abnormality increases significantly the risk of fetal chromosomal abnormalities. It is also suggested that a normal ultrasonographic examination in an otherwise at -risk patient will significantly reduce the risk of fetal chromosomal abnormalities. Ultrasonography, Chromosomal abnormalities, Genetic amniocentesis and fetal anomalies. 285 288 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-125&slc_lang=en&sid=1 SR DADGAR 20031947532846006706 20031947532846006706 Yes From the Department of Obstetrics and Gynecology, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran. MH . BADAKHSH 20031947532846006707 20031947532846006707 No A AMINI 20031947532846006708 20031947532846006708 No SH DADGAR 20031947532846006709 20031947532846006709 No