Obstetric ultrasonographic findings and fetal chromosomal abnormalities: Refining the association

OBJECTIVE: In an attempt to refine the role of ultrasonography in screening and identifying fetuses at risk for chromosomal abnormalities, a retrospec tive review of patients undergoing genetic amniocentesis was undertaken. STUDY DESIGN: Computer databases from the perinatal biology laboratory and cytogenetics laboratory of our institution were correlated to compare the r esults of the fetus' ultrasonographic examination with the cytogenetic resu lts from amniocentesis. Univariate and multivariate analysis were used to d etermine the best correlations between ultrasonographic findings and chromo somal abnormalities (study 1). The results were used to construct regressio n analysis formulas and a Neural Network program to predict the presence or absence of chromosomal abnormalities in a second set of patients (study 2) undergoing genetic amniocentesis. RESULTS: One hundred twenty-five chromosomal abnormalities were found in 37 75 fetuses in study 1 (3.3%). Multivariate analysis showed significant corr elations between anomalies of the central nervous system, heart, face and n eck, and extremities and increased nuchal fold, increased bowel echogenicit y, abnormal biparietal diameter-to-femur ratio, and the presence of chromos omal abnormalities. Regression equations and a Neural Network program succe ssfully predicted the presence or absence of fetal chromosomal abnormalitie s in a second set of 901 at-risk fetuses. CONCLUSION: A normal ultrasonographic examination result in patients who ar e at increased risk for fetal chromosomal abnormalities reduces the risk 2- to 3-fold, whereas the presence of any major ultrasonographic abnormality or certain minor abnormalities significantly increases the risk. The applic ation of these results to low-risk patients is still premature.