Fetal choroid plexus cysts: beware the smaller cyst

Area of Science:

• Maternal-Fetal Medicine
• Prenatal Diagnosis
• Genetics

Background:

• Current recommendations for amniocentesis in fetuses with choroid plexus cysts (CPCs) are based on size (≥1.0 cm) and bilaterality.
• The actual incidence and karyotype associations of CPCs may be underestimated by existing literature.

Purpose of the Study:

• To evaluate the incidence of CPCs in a large cohort.
• To determine the association between CPC characteristics (size, laterality) and fetal karyotype abnormalities.
• To reassess the criteria for recommending amniocentesis in fetuses with CPCs.

Main Methods:

• Retrospective analysis of 3,769 patient records.
• Identification and categorization of choroid plexus cysts based on size and laterality.
• Review of amniocentesis results and karyotype findings for affected fetuses.

Main Results:

• Choroid plexus cysts were identified in 2.3% of fetuses, a rate three times higher than previously reported.
• Of 83 fetuses undergoing amniocentesis, 7.2% had abnormal karyotypes, including trisomy 18, mosaic Turner syndrome, and trisomy 21.
• Abnormal karyotypes were found in fetuses with CPCs smaller than 1.0 cm, including unilateral cysts.

Conclusions:

• Fetal karyotyping may be indicated even in the presence of small or unilateral choroid plexus cysts.
• Current guidelines for amniocentesis based solely on CPC size and bilaterality may require re-evaluation.
• These findings complicate the decision-making process for recommending prenatal genetic testing.