What causes bilateral choroid plexus cysts in the fetus?
Nov 19, 2025
Source: Cainiu Health
Dr. Zhang Lu
Introduction
The formation of bilateral choroid plexus cysts in the fetus is associated with impaired cerebrospinal fluid circulation, abnormal choroid plexus vasculature, chromosomal abnormalities, maternal infection during pregnancy, and placental dysfunction. Most cases are physiological; however, pathological causes should be considered in a minority of cases. If prenatal examinations reveal persistent enlargement of the cysts or accompanying abnormalities, timely medical evaluation is recommended for further assessment.
The formation of bilateral fetal choroid plexus cysts is associated with impaired cerebrospinal fluid (CSF) circulation, abnormal choroid plexus vasculature, chromosomal abnormalities, maternal infection during pregnancy, and placental dysfunction. Most cases are physiological, while a minority may indicate underlying pathological conditions. If prenatal examinations reveal persistent enlargement of the cysts or accompanying abnormalities, timely medical evaluation is recommended for further assessment.
1. Impaired cerebrospinal fluid circulation: During early embryonic development, the choroid plexus plays a key role in CSF production and storage. If the CSF circulation pathways are not yet fully developed or are temporarily obstructed, fluid accumulation can occur, leading to cyst formation. These cysts typically resolve spontaneously as development progresses.
2. Choroid plexus vascular abnormalities: Immature development or minor malformations of blood vessels within the choroid plexus may impair local blood return, causing leakage and accumulation of tissue fluid, resulting in bilateral symmetric cysts. These usually have no significant adverse effects.
3. Chromosomal abnormalities: In rare cases, choroid plexus cysts are linked to chromosomal abnormalities such as trisomy 18 or trisomy 21 (Down syndrome). These cysts may persist and are often accompanied by other structural anomalies, necessitating prenatal diagnostic testing for exclusion.
4. Maternal infection during pregnancy: Maternal viral infections such as cytomegalovirus or rubella virus may cross the placenta and affect fetal choroid plexus development, triggering cyst formation. Diagnosis often requires evaluation alongside specific infection markers.
5. Placental dysfunction: Impaired placental function may lead to inadequate nutrient supply or metabolic disturbances in the fetus, indirectly affecting choroid plexus development and increasing the likelihood of cyst formation. Monitoring of placental function and fetal growth is essential.
Most physiological choroid plexus cysts require no specific treatment and can be managed with routine prenatal monitoring, typically resolving spontaneously after 28 weeks of gestation. Pregnant women should maintain regular作息 (sleep-wake cycles), follow a balanced diet rich in nutrients, avoid exposure to harmful substances, and maintain emotional stability to support healthy fetal development.
