# Handbook of Genetic Counseling/Choroid Plexus Cysts on Ultrasound

Choroid Plexus Cysts on Ultrasound

## Introduction and Contracting

* Ask how the pregnancy is going
* Ask about dates
* Explain the session
** Getting family hx/pregnancy hx
** Talking about what a chorioid plexus cyst is and what it means for the pregnancy, testing that may be offered
** What questions do you have?

## Pregnancy hx

* Any illnesses?
* Any infections/exposures?
* Any medications?
* Verify dates
* Screening tests up to now…ultrasounds? Triple screen test?

## Family hx (probably at end of session)

* Get two generation pedigree
* Determine any risks to pregnancy
* Specify any particular ethnic concerns as well

## Choriod Plexus Cysts (probably at beginning of session)

* What have you heard about them?
* The Choroid plexus
** A spongy layer of cells and blood vessels along the edge of the ventricles (pockets or spaces in the brain
** Produces the cerebrospinal fluid that fills the ventricles and provides a cushion to the brain and spinal cord.
** Development starts at 6th week
** By 9th weeks the choroids plexus fills ~75% of lateralventricles
** Starts to slowly decrease in size and by 20th week the chorioid plexus has assumed its adult form
* Choriod Plexus Cysts
** Description
*** Caused by folding of the spongy layer = trapping fluid in the area
*** BENIGN!!! They do not cause any problems for the fetus
*** Usually <1cm in size
*** Can be unilateral or bilateral
*** Usually can be detected by 11th week of pregnancy
*** usually resolve by the 24-28th week of pregnancy
** Incidence
*** Found in 1% of pregnancies scanned between the 16th - 20 week.
*** Found in 50% of autopsies (fetuses, adults, elderly)
* Association with chromosomal abnormalities
** HIGHLY controversial
** Trisomy 18
*** ~45% of fetuses with Trisomy 18 had chorioid plexus cysts
**** does not depend on gestational age, unilateral or bilateral or size
*** 1-2% risk of a chromosomal abnormality when CPC are found. Most likely Trisomy 18 if anything
*** TRISOMY 18 the syndrome
**** Describe genes and chromosomes
**** 1/3000-1/7000 live births
**** most do not survive to term
**** if live birth, usually die in days,weeks following birth
**** 90% die within the first year of live
**** severe congenital anomalies
** 90% heart defects
**** severe mental retardation
*** 70-77% babies with Trisomy 18 will have other findings on ultrasound (some studies say ~100% after 24 weeks)
**** clenched fists
**** heart defects
**** rocker-bottom feet
**** omphalocele
**** hydrocephalus
** VERY CONTROVERSIAL- relation to Down syndrome (thought to be coincidental by most authors)
*** Very rarely seen to be related to CPC cysts
*** 1/660 live births
*** DS - the syndrome
**** Mild-moderate MR
**** Heart problems in 40%
**** Characteristic facial features
*** Ultrasound findings
**** Echogenic bowel
**** Femur length
**** Nuchal fold thickness

## Discussion of triple screen results (if they are present)

* SCREENING test - NOT diagnostic
* Measuring three values of proteins in the mother'sblood
* They are produced by the baby in its liver
* MoM values of 1.0 are the standard
* Maternal age and gestational age are considered
* For risks associated with Trisomy 18 = expect all three values to be low
* Your results show (no/an) increased risk over the general pop of mothers who are your gestational age.

## Risk of having a baby with Trisomy 18

* Consider maternal age
* Consider CPC
* Consider triple screen results
* Consider presence of other markers on ultrasound
* USE CHART (see attached or ask Kris for a copy of hers)

## Testing Offered

* Detailed ultrasound to look for other markers (previously discussed)
* Amniocentesis
** Risk 1/200
** Determines presence or absence of aneuploidy
** Does not guarantee a healthy baby
** Some centers debate about offering based solely on CPC

## Important Points

* 18% of unaffected fetuses will have more than just CPC on ultrasound!!!!!

## Notes

The information in this outline was last updated in 2001.