A sonographic and karyotypic study of second-trimester fetal choroid plexus cysts.

A prospective study was undertaken of 513 women between 15.6-24.1 weeks' gestation who had a level II ultrasound examination followed immediately by a genetic amniocentesis. The presence or absence of fetal choroid plexus cysts was noted and the results correlated with the fetal karyotype. Thirteen cases of choroid plexus cysts were observed sonographically, a prevalence of 2.5%. The size of the cysts ranged from 3-10 mm, with a median of 6 mm. There were no other sonographically detectable congenital abnormalities in these 13 cases, and the fetal karyotype was normal in all. An association between fetal choroid plexus cysts and autosomal trisomies was not found in this series.