Isolated fetal choroid plexus cysts and karyotype analysis: is it necessary?

The purpose of this study was to evaluate the risk of fetal aneuploidy in the presence of isolated choroid plexus cysts and to evaluate the results obtained from our institution and those reported previously in the English literature. All patients with fetal choroid plexus cysts on prenatal ultrasonography were offered genetic counseling and amniocentesis for fetal karyotyping. Seven of 274 fetuses, 2.6% (95% confidence interval = 1.0 to 5.2%), with isolated choroid plexus cysts were aneuploid. Literature analysis located 23 other reports of 1537 fetuses with isolated choroid plexus cysts; 26 were karyotypically abnormal, 1.7% (95% confidence interval = 1.0 to 2.4%). When evaluating only those patients whose indication for amniocentesis was choroid plexus cysts (i.e., eliminating those patients with advanced maternal age or abnormal serum screening) the risk of having a fetus with trisomy 18 changed little, 1.9% (95% confidence interval = 0.4 to 5.5%). Our data, combined with those of the literature, suggest that the risk of finding an abnormal fetal karyotype in the presence of isolated choroid plexus cysts is at least 1% and may be as high as 2.4%. On the basis of these results, genetic counseling and prenatal diagnosis should be offered to these patients.