The choroid plexus is the part of the brain which makes cerebrospinal fluid. Cerebrospinal fluid normally bathes and protects the spinal column and brain. In about 1 – 2 per cent of normal babies (1 out of 50 – 100), a tiny bubble of fluid is pinched off as choroid plexus forms. This looks like a cyst inside choroid plexus at the time of the ultrasound.
The doctor typically notices a choroid plexus cyst on an ultrasound scan during the second trimester of pregnancy. This type of cyst develops in about 1 to 2 per cent of pregnancies. It usually does not cause any health issues and resolves on its own before a baby is born. Doctors notice these cysts in both males and females.
This blog explains a choroid plexus cyst, its causes, symptoms, risk factors, complications, treatment and prevention.
What is a choroid plexus cyst?
A choroid plexus cyst is a small accumulation of fluid that develops on the choroid plexus of an unborn baby’s brain. The choroid plexus is a network of cells and blood vessels in different spaces filled with fluid in the brain, known as ventricles. A thin layer of cells is responsible for producing cerebrospinal fluid that covers every blood vessel.
What are the causes of a choroid plexus cyst?
A choroid plexus cyst can develop if the fluid is trapped in the layers of cells of the choroid plexus. It can occur due to several reasons.
The formation of a choroid plexus cyst is similar to a blister that forms beneath the skin. The choroid plexus cyst starts to develop at around six weeks of gestation. The doctor can see the cyst on an ultrasound around the 25th week of pregnancy.
What are the complications of a choroid plexus cyst?
The choroid plexus is part of the brain that does not influence a person’s intelligence or cognitive development. Therefore, a cyst in the choroid plexus carries no health risk or intellectual disorders.
In about a third of the cases, choroid plexus cysts develop in fetuses with trisomy 18, also called Edwards syndrome. It is a condition in which a fetus contains three copies of chromosome 18 rather than two.
The embryo may inherit the extra chromosome from a parent, or the extra chromosome may develop at conception. It causes a lot of health issues. Several fetuses with trisomy 18 do not survive till birth due to organ abnormalities. Babies born with trisomy 18 tend to have significant congenital disabilities, including:
- Heart problems
- Clenched fists
- Small mouths
- Abnormally shaped heads
- Problems feeding and breathing
While several fetuses with trisomy 18 also contain choroid plexus cysts, only a tiny fraction of fetuses with a choroid plexus cyst also have trisomy 18.
When to seek medical attention?
Regular prenatal checks and screening usually detects choroid plexus cysts and trisomy 18-related issues.
How is a choroid plexus cyst treated?
Usually, a choroid plexus cyst does not require treatment since most cysts disappear on their own by the 28th week of gestation. A healthy baby with a choroid plexus cyst is likely to develop normally. The surgery to eliminate the cyst is typically used in rare cases if it is a cancerous tumour called choroid plexus carcinoma (CPC).
When women are worried about the possibility of their unborn baby suffering from trisomy 18, they can consult the doctor so that they can perform a test known as amniocentesis. It is a test where doctors draw amniotic fluid from the uterus with a needle. The doctor tests the amniotic fluid to monitor for signs of genetic issues that could impact the baby’s health.
To rule out the probability of the baby having trisomy 18, the doctor can also perform an alpha-fetoprotein(AFP) test, which examines the protein levels in the woman’s blood. Doctors usually perform the AFP test anytime between the 15th and 20th week of pregnancy. Typically, it takes around one or two weeks to get the results. Unlike amniocentesis, an AFP test carries no additional risks. Doctors usually suggest the AFP test if they believe there is an increased risk of the unborn baby suffering from a congenital disorder. If the scan and the AFP test are not conclusive , then amniocentesis can clarify the state of the baby’s health before they are born.
Studies performed on children suffering from a detectable choroid plexus cyst that disappeared showed that they did not display any ongoing cognitive problems.
An abnormal test result can increase the worries of pregnant women. However, if doctors discover a choroid plexus cyst, particularly in a normally developing fetus, women must not get concerned. In a small percentage , the cysts could form in babies with trisomy 18, which leads to various neurological and developmental problems. The cysts carry no health risks, and most babies with the cysts have a healthy birth and develop normally.
Frequently Asked Questions (FAQs)
1. Does the size of the choroid plexus cyst matter?
Typically, the choroid plexus cyst size does not matter. However, several large cysts are a cause for concern.
2. What are the risks of amniocentesis?
The probable risks of undergoing an amniocentesis to detect trisomy 18 include the following:
- Uterine infection
- Amniotic fluid leaks through the vagina
- Miscarriage, though the risk is significantly less
- Injury to the baby when doctors insert the needle or when the baby moves its arms or legs while performing the procedure
- Transmission of infection from a woman to the baby
- The baby’s blood cells can get into the woman’s bloodstream
3. Are choroid plexus cysts harmful to the baby?
Doctors consider choroid plexus cysts to be a part of normal human variation. The cysts do not harm the baby. These cysts also do not damage the brain.