CHOROID PLEXUS CYST

CHOROID PLEXUS CYST

The choroid plexus is the part of the brain that makes the fluid that bathes and nourishes the brain. A CPC is a tiny “bubble” or “pocket” of fluid inside the choroid plexus that can be seen on ultrasound. There may be one or multiple CPCs.

Choroid plexus cysts are nonneoplastic cysts lined by cells that are morphologically similar to those of the epithelium in the CNS. They have various names: ependymal cysts, neuroepithelial cysts, choroidal-epithelial cysts, and subarachnoid-ependymal cysts (Czervionke CF, Daniels DL, Meyer GL, Pojunas KW, Williams AL, Haughton VM. Neuroepithelial cysts of the lateral ventricles: MR appearance. AJNR 1987;8:609-613).

They are found in 1-2% (1 in 50 to 1 in 100) of pregnancies. Most CPCs will go away before delivery; however even if they do remain, they do not have any effect on the pregnancy and do not require follow up. CPCs have also been seen in imaging of healthy individuals and do not have any long term effects.

If a CPC is the only finding seen on ultrasound, it is thought to be normal variation of the baby’s development. Rarely a baby with a CPC may have a chromosome condition such as Trisomy 18. Trisomy 18 is a genetic condition that causes many birth defects, severe developmental problems and life limiting health concerns. However, most babies with trisomy 18, will usually have other ultrasound findings or abnormal blood testing results.

In most pregnancies, this finding does not significantly increase the chances of a chromosome condition. If you have already had normal blood testing (such as non-invasive prenatal testing, first trimester screening or quad screening) and a CPC is the only finding on ultrasound, the chance for a chromosome condition is still well under 1% and additional testing and ultrasounds are not indicated. If you have not had any testing for chromosome conditions in the pregnancy, there are tests available to provide additional information about these risks now that a CPC has been identified on ultrasound (University of Texas health science center at Houston).

Professor Kypros Nicolaides. Fetal medicine foundation UK said that when other defects are present, there is a high risk of chromosomal defects, usually trisomy 18 and trisomy 21.

With the presence of CPSCs, caregivers should next evaluate maternal age risk and if available, the maternal serum screen. 2 CPCs increase the risk for trisomy 18. Referral for counseling and possible invasive testing is only necessary if maternal age is 35 years or older or the maternal serum screen is positive for either trisomy 18 or 21.

SOGC clinical practice guidelines

1.       Choroid plexus should be evaluated for the presence of discrete cysts during the 16-20 week ultrasound.

2.       Isolated CPCs require no further investigation when maternal age or the serum screen equivalent is less than the risk of a 35 year old.

3.       Fetal karyotyping should only be offered if isolated CPCs are found in women 35 years or older or if the maternal serum screen is positive for either trisomy 18 or 21.

4.       All women with fetal CPCs with additional malformation should be offered referral and karyotyping.

5.       All women with CPCs and additional soft markers should be offered additional counseling and further ultrasound.