choroid plexus cysts

[Guest guest]

What is the choroid plexus?

The choroid plexus refers to the area in the brain which makes the fluid that

bathes the brain and spinal cord (cerebrospinal fluid). The choroid plexus is

not an area of the brain involved in thinking.

What are choroid plexus cysts?

Choroid plexus cysts are fluid-filled spaces in the choroid plexus. They are

seen in about 1% (1/100) of all second trimester ultrasounds. Choroid plexus

cysts may be seen in one or both sides of the brain. The number, size, and shape

of the cysts may vary. Choroid plexus cysts are also found in healthy children

and adults.

What do choroid plexus cysts mean for the baby?

When choroid plexus cysts are detected in a fetus, they usually disappear on

their own by 24-26 weeks of pregnancy. They are not known to interfere with

normal brain development or cause brain damage. Choroid plexus cysts are not

tumors or cancer.

It is most likely that the choroid plexus cysts are normal for your baby and you

will have a normal, healthy child. However, some researchers have seen an

association between these cysts and a chromosome abnormality called Trisomy 18

(click here to go to the Trisomy 18 section).

The chance that a fetus with isolated choroid plexus cyst(s) has Trisomy 18 is

felt to be about 1% or less if the rest of the ultrasound exam was normal. This

means that there is a 99% or greater chance that the fetus does not have a

chromosome abnormality. Choroid plexus cysts do not cause Trisomy 18: rather,

they are a sign that the fetus may have a somewhat higher chance of having that

condition.

What are chromosome abnormalities?

Chromosomes are the packages of genetic information found in every cell of the

body. They contain genes that are responsible for growth and development.

Normally there are 46 chromosomes in every cell. Extra or missing chromosome

material almost always causes mental retardation and physical abnormalities.

Chromosome abnormalities are usually the results of an accident of nature and

there is nothing that you can do to cause them or prevent them from occurring.

Chromosome abnormalities cannot be fixed or cured by medicine or surgery. Every

woman has a risk to have a baby with a chromosome abnormality, but the risk

increases as a woman gets older.

Trisomy 18 occurs when there is an extra copy of chromosome 18. Many fetuses

with this condition die before they are born. Children with Trisomy 18 are

severely mentally retarded and may have many physical birth defects. Most

children with Trisomy 18 die before 1 year of age.

Can ultrasound detect Trisomy 18?

Ultrasound allows us to see some physical birth defects in the fetus. Most, but

not all, babies with chromosome abnormalities have birth defects that can be

seen on ultrasound. Although a normal ultrasound is reassuring, it does not

guarantee that there are no birth defects or mental retardation.

How are chromosome abnormalities diagnosed?

A test called amniocentesis can tell with over 99% accuracy if the fetus has a

chromosome abnormality.

During an amniocentesis a thin needle is inserted through the woman's abdominal

wall into the uterus under ultrasound guidance. A small amount of the fluid

surrounding the baby is removed. Fetal cells from the fluid are grown in the

laboratory and the fetal chromosomes are studied. The results are usually ready

in 2 weeks.

Amniocentesis, when performed between 15 and 22 weeks of pregnancy, has a

1/200-1/300 risk for miscarriage or serious complications. This means that over

99.5% of the women who have this test will not have any pregnancy complications

because of this procedure. Amniocentesis is a voluntary test, and your genetic

counselor will discuss it with you in more detail.

Is any other testing needed?

If you decide to have an amniocentesis and the results are normal, no further

testing is necessary. The choroid plexus cyst is then considered a normal

variation which is not known to be harmful to the baby.

Every pregnant couple has a 3% risk for having a baby with a birth defect. It is

not possible to test for all birth defects. However, please remember that 97% of

all babies are born healthy and normal.

If you have any further questions, please call the Kaiser Permanente Genetics

Department in your area:

Oakland

Sacramento

San Francisco

San