Choroid plexus cysts (CPC) are unilocular cysts usually located in the posterior thick portion of choroid plexus

CPC are most often incidental isolated findings

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  Almost all resolve by 32 weeks

  
  
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  Might be large, multiple, or bilateral

  
  
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  Not associated with aneuploidy in low-risk patients

CPC may be seen in trisomy 18 (T18)

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  Anomalies and growth restriction almost always present

  
  
  
  
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    Cardiac and extremity anomalies common

  
  
  
  
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  CPC > 10 mm associated with mild ↑ risk for T18

  
  
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  Multiple and bilateral CPC do not ↑ risk for T18

Intraventricular hemorrhage

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  Blood clot adherent to choroid might mimic CPC

  
  
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  Echogenic ventricular wall, ventriculomegaly

Choroid plexus papilloma (rare)

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  Vascular mass, ventriculomegaly

Is patient low risk for aneuploidy? Has she had testing?

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  Cell-free DNA test results (best)

  
  
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  Maternal serum biochemistry results

  
  
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  Consider genetic counseling if patient has had no testing

Follow-up to show CPC resolution is not necessary

Do detailed scan of fetus when CPC is seen

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  Extra cardiac views

  
  
  
  
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    Outflow and inflow tract views

  
  
  
  
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  Extra extremity views

  
  
  
  
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    Open hands, normal feet

  
  

Scan in multiple planes to show cyst located in choroid

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  Large cysts may be mistaken for ventriculomegaly

  
  
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  Normal fluid-filled atria may mimic CPC