Prenatal sonographic findings in trisomy 13, 18, 21 and 22. A review of 46 cases.

A study of 46 patients with trisomic fetuses was performed to determine if there are one or more second-trimester ultrasonic findings predictive of aneuploidy. Videotapes of ultrasonography performed prior to amniocentesis on the 46 fetuses with autosomal trisomy and from a control group of 50 chromosomally normal fetuses were reviewed without knowledge of the karyotype. Fetuses with autosomal trisomies had short long bones, especially femurs, as well as high biparietal diameter/femur length ratios. In addition, a nuchal thickness of > 5 mm, abnormal heart anatomy, slight pyelectasis, increased bowel echogenicity and/or abnormal flexion of the hands were all predictive of autosomal trisomies.