Choroid plexus cysts (CPC) can be an isolated finding, which confers a 1% (variable based on population studied) risk
of fetal aneuploidy. The risk
of aneuploidy increases to 10.5-12% if other risk factors or ultrasound findings are noted. The particular size, bilaterality, disappearance/progression or the position of the CPC, do not have any effect on the risk of aneuploidy. 44-50% of Edwards syndrome (trisomy 18) cases will present with CPC, and 1.