During pregnancy, routine ultrasound examinations sometimes reveal findings that can sound worrying at first, especially when they involve the developing baby’s brain. One such finding is bilateral choroid plexus cysts during pregnancy, which are small fluid-filled spaces seen in the choroid plexus of the fetal brain. Although the term may appear complex and concerning, in many cases these cysts are harmless and resolve on their own as the pregnancy progresses. Understanding what they mean, why they appear, and how doctors evaluate them can help expecting parents feel more informed and reassured during prenatal care.
Understanding Bilateral Choroid Plexus Cysts During Pregnancy
Bilateral choroid plexus cysts during pregnancy refer to small, fluid-filled sacs found on both sides (bilateral) of the choroid plexus, a structure inside the fetal brain that produces cerebrospinal fluid. These cysts are typically detected during a second trimester ultrasound scan, often around 18 to 22 weeks of gestation. They are not brain abnormalities in themselves, but rather a variation that can appear during normal brain development.
What Are Choroid Plexus Cysts?
The choroid plexus is a network of cells in the brain responsible for producing cerebrospinal fluid, which cushions and protects the brain and spinal cord. Sometimes, small pockets of fluid become trapped within this tissue, forming what are known as choroid plexus cysts. These cysts are usually tiny and do not interfere with brain function or development. In most pregnancies, they disappear naturally before birth or shortly after delivery.
Why Are They Called Bilateral?
The term bilateral simply means that cysts are present on both sides of the choroid plexus in the brain. It is also possible for cysts to appear on only one side, which is called unilateral. However, whether they are unilateral or bilateral, the presence of these cysts alone does not usually indicate a problem with the baby’s health.
Causes of Choroid Plexus Cysts in Fetal Development
The exact cause of bilateral choroid plexus cysts during pregnancy is not fully understood, but they are believed to result from normal developmental processes in the fetal brain. As the choroid plexus produces fluid, small spaces may temporarily form and become visible on ultrasound. These cysts are considered a common incidental finding rather than a disease.
Several factors may influence their appearance, including
- Normal variation in fetal brain development
- Temporary fluid trapping in brain tissue
- Timing of fetal growth at the moment of ultrasound examination
In most cases, no external or maternal factors such as diet, stress, or activity are known to cause these cysts.
Detection During Pregnancy Ultrasound
Bilateral choroid plexus cysts during pregnancy are usually discovered during a routine fetal ultrasound, often referred to as the anomaly scan or second trimester scan. This scan is performed to assess the baby’s anatomy, growth, and overall development.
On ultrasound images, these cysts appear as small dark (anechoic) spaces within the choroid plexus. They are typically well-defined and located symmetrically when bilateral. In many cases, the ultrasound report will mention them as an incidental finding, meaning they were observed but are not the main concern.
What Doctors Look For
When choroid plexus cysts are detected, healthcare providers usually assess whether
- The cysts are isolated (no other abnormalities present)
- There are any additional soft markers or structural changes
- The baby’s growth and anatomy are normal overall
An isolated finding generally carries a much better prognosis than cases where multiple findings are present.
Are Bilateral Choroid Plexus Cysts Dangerous?
For most pregnancies, bilateral choroid plexus cysts are not dangerous and do not affect brain function, intelligence, or long-term development of the baby. They are often considered a normal variant that resolves on its own. Many babies born with these cysts show completely normal health outcomes.
However, in some cases, choroid plexus cysts can be associated with chromosomal conditions, particularly when they are found alongside other ultrasound markers. This is why doctors may recommend further evaluation if additional findings are present.
Association With Chromosomal Conditions
Choroid plexus cysts have been studied in relation to certain genetic conditions, most notably trisomy 18 (Edwards syndrome). It is important to understand that the presence of bilateral choroid plexus cysts during pregnancy alone does not mean the baby has a chromosomal disorder.
In fact, when these cysts are isolated and no other abnormalities are detected, the risk of chromosomal conditions remains very low. Concerns usually arise only when additional markers are seen in ultrasound, such as heart defects or growth restrictions.
Doctors often use a combination of ultrasound findings, maternal age, and screening tests to determine whether further genetic testing is needed.
Follow-Up Tests and Monitoring
If bilateral choroid plexus cysts are found, the next steps depend on whether they are isolated or associated with other findings. In many cases, no additional testing is required other than routine prenatal care. However, some situations may lead to further evaluation.
Possible Follow-Up Options
- Repeat ultrasound after a few weeks to check if the cysts have resolved
- Non-invasive prenatal testing (NIPT) to screen for chromosomal conditions
- Detailed anatomy scan for a closer look at fetal development
- Genetic counseling if risk factors are present
Most choroid plexus cysts disappear by the third trimester, and follow-up scans often confirm that the baby’s brain appears completely normal.
Prognosis and Long-Term Outcomes
The prognosis for bilateral choroid plexus cysts during pregnancy is generally excellent. When found in isolation, they are considered a benign finding with no expected impact on neurological development. Babies born after such findings typically grow and develop normally without any complications linked to the cysts.
Even when cysts persist for a short time, they usually resolve spontaneously. The brain continues to develop normally, and the presence of these cysts does not indicate structural brain damage or future learning difficulties.
Emotional Impact on Expecting Parents
Hearing that something unusual has been found during an ultrasound can create anxiety for expecting parents. The term brain cyst may sound alarming, even when doctors explain that it is usually harmless. It is natural to feel worried, especially during pregnancy when the focus is on the baby’s health and safety.
Clear communication with healthcare providers can help reduce stress. Understanding that bilateral choroid plexus cysts during pregnancy are often a temporary and benign finding allows many parents to feel reassured. Asking questions during prenatal visits and discussing any concerns openly can also provide emotional comfort.
When to Seek Further Advice
Although most cases do not require intervention, there are situations where further medical advice is important. Parents should follow up with their healthcare provider if
- Additional abnormalities are detected in ultrasound scans
- There is a family history of genetic conditions
- Screening tests suggest increased risk
- There are ongoing concerns about fetal growth or development
In such cases, doctors may recommend additional testing or refer the patient to a specialist for more detailed evaluation.
Bilateral choroid plexus cysts during pregnancy are a relatively common ultrasound finding that often causes unnecessary worry. In most situations, they are harmless, temporary, and resolve on their own without affecting the baby’s health or development. While they can occasionally be associated with chromosomal conditions, this risk is generally low when no other abnormalities are present. With proper prenatal care, follow-up, and guidance from healthcare professionals, expecting parents can better understand this condition and feel more confident throughout their pregnancy journey.