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.