Choroid plexus cyst in pregnancy

By trimester

Weeks 1–13

1st trimester

Choroid plexus cysts are generally identified during second-trimester ultrasound rather than first-trimester symptoms. First-trimester or cell-free DNA screening results still matter later because they help determine whether an isolated cyst changes aneuploidy counseling. The cyst itself cannot be felt and does not cause maternal symptoms.

Weeks 14–27

2nd trimester

Most choroid plexus cysts are found at the anatomy scan. The key question is whether the cyst is truly isolated after a detailed ultrasound and whether trisomy 18 screening has already been low risk. With no prior screening, current guidance offers screening options; with additional abnormalities, genetic counseling and diagnostic testing discussion are appropriate.

Weeks 28–birth

3rd trimester

An isolated cyst often disappears before the third trimester, and resolution is not what determines chromosome risk. With negative serum or cell-free DNA screening and no other findings, SMFM recommends no follow-up ultrasound or postnatal evaluation solely for the cyst. New growth or structural findings should be considered separately.

What does the evidence show for choroid plexus cyst?

• SMFM defines an isolated soft marker as one found without a structural anomaly, growth restriction, or another soft marker after detailed ultrasound. For an isolated choroid plexus cyst with negative serum or cell-free DNA screening, it recommends no further aneuploidy evaluation, follow-up imaging, or postnatal evaluation solely for the cyst. 1
• Current ACOG guidance says a patient with an isolated choroid plexus cyst and no prior aneuploidy screening should receive counseling and an offer of cell-free DNA screening, a serum screen when appropriate, or amniocentesis. If prior screening is low risk, no further risk assessment is needed for the isolated marker. 2
• A 2026 systematic review of 10 heterogeneous studies covering more than 10,600 screened fetuses found that isolated choroid plexus cysts in otherwise low-risk pregnancies were not significantly associated with chromosomal abnormalities, while cysts accompanied by other ultrasound findings carried substantially greater concern. 3
• A prospective follow-up compared 25 children with an isolated prenatal cyst and normal chromosomes with 45 controls at 18 months. It found no significant group differences across measured cognitive, motor, behavioral, socioemotional, activity, or cardiac autonomic outcomes, although the sample was small and follow-up was limited to toddler age. 4
• In a prospective series of 6,288 second- and third-trimester ultrasound examinations, 41 fetuses had a choroid plexus cyst. Most disappeared by 23 to 24 weeks, and additional structural abnormalities were the important reason for further evaluation. This older pre-cell-free-DNA study does not define current screening decisions. 5

When should I call my provider about choroid plexus cyst?

An isolated choroid plexus cyst is not an emergency and causes no maternal warning symptoms. Contact the prenatal team promptly if the ultrasound report also lists a structural anomaly, fetal growth restriction, another soft marker, an incomplete anatomy survey, or if aneuploidy screening was positive or has not been performed. Urgent pregnancy symptoms such as bleeding, fluid leakage, severe pain, or reduced fetal movement require immediate assessment for their own cause, not because of the cyst. When in doubt, call your obstetric team the same day. Early input almost always beats waiting, and the on-call line exists exactly for this.