• Cyst-like spaces that occur in the choroid in approximately 1-6% of fetuses between 13 and 24 weeks gestation
• Majority are small and incidental, disappearing by 26 weeks gestation
• Thought to represent entrapment of cerebrospinal fluid within an in-folding of neuroepithelium
• May be associated with chromosomal abnormalities, especially trisomy 18
  • Likelihood ratio of trisomy 18 with isolated choroid plexus cyst ranges from 0.03 to 13.8 times the mother’s background risk
  • Trisomy 18 is almost always associated with other structural abnormalities
  • When a choroid plexus cyst is identified
    • In addition to the routine anatomic survey, a targeted search for structural abnormalities should be performed

  • Amniocentesis should be offered when a fetus has both a choroid plexus cyst and additional structural abnormalities

·        Rare cases of symptomatic choroid plexus cysts causing obstructive hydrocephalus have been reported