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.