Choroid plexus cysts are pockets of fluid that occur in the spongy tissues of the brain, called the choroid plexus, that produce cerebrospinal fluid. Choroid plexus cysts have an incidence rate of 1 in 50 to 100 pregnancies, and it is estimated that they appear in 1-3% of every pregnancy between 16 and 24 weeks. Isolated choroid plexus cysts, or cysts that appear on their own and not in conjunction with other anomalies, are considered normal and typically disappear by 28 to 32 weeks’ gestation with no effects on the baby. Choroid plexus cysts are, however, considered a marker for aneuploidy, or chromosomal abnormalities, like trisomy 18, so a detailed ultrasound, maternal serum screening, or amniocentesis may be recommended to rule out additional diagnoses. 
Choroid plexus cysts
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