Choroid plexus cysts (CPCs) are cysts that occur within choroid plexus of the brain. Choroid plexus cysts (CPC's) are sometimes found on ultrasound scan at around 18 to 20 weeks gestation. Choroid Plexus Cysts are believed to derive from folding of the neuroepithelium with subsequent accumulation of CSF and debris. The choroid plexus has the important function of producing a fluid called cerebrospinal fluid. The fluid produced by the cells of the choroid plexus fills the ventricles and then flows around the brain and the spinal cord to provide a cushion of fluid around these structures.

CPCs can organize within this system and go from graceful trapped within this soft bed of cells, often like a soap bubble or a blister. CPCs are frequently called "tender signs" or fetal ultrasound "markers" because some studies have establish a feeble association between CPCs and fetal chromosome abnormalities. It is believed that many adults have one or much small CPCs. CPCs have no influence on a person's health or growth or learning. The fetal mind may produce these cysts as a natural region of growth. They are short-lived and normally are gone by the 32nd week of pregnancy.

There is considerable controversy in the medical journals about how great a risk of Trisomy 18 or other chromosomal abnormalities there is for a fetus with choroid plexus cysts. The risk of chromosome abnormalities increases significantly when CPC's are associated with other markers rising from less than 1 in 250 as an isolated finding in a woman under 32 years to 1 in 10 when associated with other markers or raised maternal age. Choroid plexus cysts are seen during 1% to 3% of all mid-trimester prenatal ultrasound examinations.

There is substantial argument in the medical journals about how good a danger of Trisomy 18 or new chromosomal abnormalities there is for a fetus with choroid plexus cysts. The danger of chromosome abnormalities increases significantly when CPC's are associated with new markers rising from little than 1 in 250 as an isolated finding in a woman under 32 years to 1 in 10 when associated with new markers or raised paternal age. Choroid plexus cysts are seen during 1% to3% of all mid-trimester prenatal ultrasound examinations.