What is Choroid Plexus Cyst?
Choroid plexus cysts are the fluid-filled spaces that occur in glands in the brain known as choroid plexus. These glands are present on both sides of the brain and are surrounded by fluid that protects the brain and spinal cord from injury.
Choroid plexus cysts develop in some fetuses and are detected on an ultrasound that is done in the second trimester of pregnancy. It is seen occurring in 1-2 pregnancies.(1) The choroid plexus cyst does not pose any risk and resolves on its own. These cysts are seen occurring both in males and females.
Causes of Choroid Plexus Cyst
Choroid plexus cysts occur when the fluid gets trapped in the layers of the cells of the choroid plexus. There can be one cyst or several of them. These cysts are like blisters that form below the skin. Choroid plexus cysts starts forming at 6 weeks of gestation and by 25 weeks it can be visible in an ultrasound.
Complications of Choroid Plexus Cyst
The choroid plexus cyst has no impact on the thinking, deducing, or on a person’s intelligence or cognitive development as the choroid plexus is not that part of the brain that is involved in all these functions.
Choroid Plexus Cyst and Trisomy 19
A choroid plexus cyst is seen occurring about a third time in the fetus with trisomy 18.
Trisomy 18 is also known as Edward syndrome, a condition in which the fetus has 3 copies of chromosome 18 instead of 2. This extra chromosome is inherited from a parent or develops randomly at the time of conception. Most of the fetuses with trisomy 18 do not survive due to organ deformity. This condition leads to birth defects, including:
- Small mouth
- Clenched fist
- Heart problems
- Abnormally shaped heart
- Problems with feeding and breathing
Only 10 percent of babies with trisomy 18 survive past their first birthday and have severe mental disabilities.(2)
Many fetuses with trisomy 18 have choroid cysts, only a small percentage with choroid cyst would have trisomy 18.
How is Choroid Plexus Cyst Treated?
There is no treatment for choroid plexus. If there is a possibility of the baby having trisomy 18, the doctor would recommend an amniocentesis.
Amniocentesis is a procedure in which a small amount of fluid is taken from the uterus using a needle. The fluid taken is examined for the signs of genetic issues that may impact the baby’s health.
There are a few risks associated with amniocentesis such as an amniotic fluid leak, miscarriage, injury to the baby, and uterine infection that should be taken into consideration before going ahead with the procedure.
Choroid plexus cyst mostly resolves in infants even if the chromosomal anomaly exists.
Another test known as the alpha-fetoprotein test can be done if the doctor suspects any congenital disorder. It poses less risk than amniocentesis. In 90 percent of fetuses the cyst resolve on its own by 28 weeks of gestation.(3) Even if a choroid cyst is detected in an otherwise healthy child, he is likely to develop normally.
Outlook of Choroid Plexus Cyst
Finding a choroid cyst in an otherwise normally developing child is not of much concern. But abnormal testing can add to the uncertainty of the pregnancy.