Prenatal cytogenetic diagnosis of trisomy 18 was followed by induced termination of a 20-week pregnancy in a 40-year-old multipara; the fetus had recognizable phenotypic stigmata of trisomy 18. Among external anomalies, those of the ears and hands were most apparent. Internal anomalies included ventricular and atrial (ostium II) septal defects, bicuspid aortic valve, abnormal configuration of liver, umbilical hernia, Meckel diverticulum, intestinal malrotation, hemivertebrae, and partial absence of the cerebral falx. Growth retardation, evident mainly in the placenta, was reflected in lower than expected weight and structural abnormalities. The findings indicate that the phenotype of trisomy 18 is well established by midgestation.
Hsu LYF, Strauss L, Dubin E, Hirschhorn K. Prenatal Diagnosis of Trisomy 18Pathologic Findings in 20-Week Conceptus. Am J Dis Child. 1973;125(2):290–292. doi:10.1001/archpedi.1973.04160020098020