A retrospective analysis of all fetuses with prenatally detected choroid plexus cysts, identified at our institution between 1988 and 1993, was performed. Cytogenetic data, associated sonographic findings, obstetric outcome and pediatric follow-up was obtained to determine the incidence of aneuploidy and the rate of associated congenital anomalies in second-trimester fetuses with this finding. There were 211 second-trimester fetuses identified with a choroid plexus cyst. Amniocentesis was performed in 175 (83%) and postnatal chromosome analysis was performed in one newborn. Follow-up data are available on 203 (96%). Of the 176 cytogenetically studied fetuses, eight (4.5%) were aneuploid (including four cases of trisomy 18). In four of the aneuploid fetuses, the choroid plexus cyst was the only abnormal sonographic finding identified (including one case of trisomy 18). From this study and a review of the literature, we confirm that choroid plexus cysts are a sonographic marker for trisomy 18, even when identified as an isolated finding in an otherwise normal-appearing fetus. We conclude that the detection of a choroid plexus cyst merits further careful evaluation of fetal anatomy and consideration of cytogenetic evaluation.
Copyright 1994 International Society of Ultrasound in Obstetrics and Gynecology