Choroid Plexus Cyst
During ultrasounds fetuses are known to occasionally have a fetal choroids plexus cyst. The small choroids plexus cysts are normally not a sign of a brain abnormality but they have been associated to certain chromosome disorders, mainly trisomy 18. Most choroids plexus cysts resolve without any treatment and leave behind no consequences of their appearance. However, rarely severe mental retardation can occur.
What is a Choroids Plexus Cyst?
One to two percent of normal fetuses develop a choroids plexus cyst. The cyst occurs on the part of the brain that is responsible for making cerebrospinal fluid called the choroids plexus. The fluid it produces protects the body’s brain and spinal column. A choroids plexus cyst occurs when a bubble of fluid is isolated as the choriod plexus develops. This then takes the form of a cyst, resembling a blister. Fetal choriod plexus cysts are noticed because they are visible on ultrasounds.
Choroid Plexus Cyst Tests
Although small choroid plexus cysts are considered to be normal, the risk of complications increase if the cysts are large or multiple in numbers. There are tests that can be preformed to determine whether or not a cyst can be a complication for a fetus. An amniocentesis can be performed to determine the number of chromosomes a fetus has to rule out any chromosome disorders. If these tests discover an extra chromosome 18, there is likely to be a chromosome disorder. There is an increased risk of miscarriage if an amniocentesis is performed.
Risks of Choroid Plexus Cysts
Although most of theses cysts are harmless under certain circumstances choriod plexus cysts can be associated to chromosome disorders. The main disorder they can be associated with is trisomy 18. Most of the fetuses with and extra trisomy 18 chromosome are stillborn. Those that do survive suffer from extreme mental retardation. This condition can also cause physical deformities as well. This condition only affects about one out of every three thousand choriod plexus cyst cases.
If a fetus has a choroid plexus cyst there is normally no reason for concern. Because of the high risk of miscarriage from amniocentesis testing many choose not to have the testing done. In a majority of the cases, the fetuses will continue to develop normally into healthy infants. The risk of severe complications is extremely low. Most feel comforable in their choice if they choose not to have a amniocentesis test done and there are normally no further complications.
“Prenatal Diagnosis” August 6, 2008 ucsfhealth.org