IDENTIFICATION OF 2ND-TRIMESTER FETUSES WITH AUTOSOMAL TRISOMY BY USE OF A SONOGRAPHIC SCORING INDEX

PURPOSE: To evaluate the ability to identify fetuses with autosomal trisomy by use of sonographic features in the form of a scoring system. MATERIALS AND METHODS: The presence of nuchal thickening, longbone shortness, pyelectasis, hyperechoic bowel, choroid plexus cyst, and major anatomic defects was prospectively evaluated in 60 trisomic fetuses aged 14-21 weeks and 106 second-trimester control fetuses. RESULTS: Forty-five fetuses had Down syndrome, 13 had trisomy 18, and two had trisomy 13. Based on previous criteria for short femur and humerus, pyelectasis, nuchal thickening, echogenic bowel, and choroid plexus cysts, a scoring system for detection of aneuploidy was developed. it enabled identification of 33 fetuses with Down syndrome (73%), 11 (85%) with trisomy 18, two (100%) with trisomy 13, and four control fetuses with abnormality (4%). The positive predictive value in patients in 1/250, 1/500, and 1/1,000 risk groups was 7.2%, 3.7%, and 1.9% for identification of a fetus with Down syndrome. CONCLUSION: These sonographic markers seem to be sensitive for the detection of chromosomal abnormalities.