The choroid plexuses are structures in the ventricles (spaces) of the brain that produce the cerebrospinal fluid. Each plexus is made up of a network of capillary blood vessels covered by transporting epithelial cells. Occasionally fluid becomes trapped and forms pockets in the choroid plexus. These pockets of fluid are called  choroid plexus cysts (CPC). Choroid plexus cysts are seen during 1% to 3% of all mid-trimester prenatal ultrasound examinations [1]. The cysts may be seen in one or both sides of the brain, and generally have no
effect on fetal development. However, choroid plexus cysts do have a weak association with fetal chromosome abnormalities.

What Causes Choroid Plexus Cysts?

Choroid plexus cysts are believed to be caused by abnormal folding of the epithelium lining of the choroid plexus which traps fluid and debris [2,3].

Does it Need Treatment?

More than 90% of choroid plexus cysts resolve spontaneously by 28th weeks' gestation .  Once resolved, the cysts do not recur. [1,4]. The finding of isolated choroid plexus cysts is not associated with delayed infant or early childhood development [5]. Rarely very large cysts may cause obstruction of the cerebrospinal fluid which may need treatment after the infant is born.


What is the Risk of Chromosomal Abnormality? [6-10]

Choroid plexus cysts are most strongly associated with trisomy 18 (Edward syndrome). Trisomy 18 (Edward syndrome) is a disorder characterized by severe mental retardation and multiple abnormalities, such as cleft lip and palate, small jaw (micrognathia), low set ears, club feet, clenched fists, intrauterine growth restriction, single umbilical artery, elevated amniotic fluid ( polyhydramnios), and kidney abnormalities. More than 90% of fetuses have a heart defect. The condition is not compatible with life, and only 5% to 10 % of infants survive the first year after delivery.

In the presence of an otherwise normal ultrasound examination the finding of an isolated choroid plexus cyst is not likely to be of any clinical significance. When an isolated choroid plexus cyst is detected on examination the American College of Obstetricians and Gynecologists recommends amniocentesis is necessary "only if serum screening results are abnormal or the patient is older than 32 years at delivery"

REFERENCES

1. Peleg D and Yankowitz J. Choroid plexus cysts and aneuploidy.J Med Genet. 1998;35:554-7.PUBMED
2. Guariglia L, Rosati P. Prevalence and significance of isolated fetal choroid plexus cysts detected in early pregnancy by transvaginal sonography in women of advanced maternal age. Prenat Diagn. 1999;:128-131. PUBMED
3. Shuangshoti S, Netsky MG. Histogenesis of choroid plexus in man.
Am J Anat. 1966;118:283-316.  PUBMED
4. Chitkara U Choroid plexus cysts in the fetus: a benign anatomic variant or pathologic entity? Report of 41 cases and review of the literature.
Obstet Gynecol. 1988;72:185-9. PUBMED
5. Digiovanni LM, Choroid plexus cysts: infant and early childhood developmental outcome.
Obstet Gynecol. 1997;90:191-4.PUBMED
6. Burrows A Choroid plexus cysts in the fetal brain. Aust N Z J Obstet Gynaecol. 1993 ;33:262-4. PUBMED
7. Bromley B, Choroid plexus cysts: not associated with Down syndrome.Ultrasound Obstet Gynecol. 1996;8:232-5. PUBMED
8. Yoder PR The second-trimester fetus with isolated choroid plexus cysts: a meta-analysis of risk of trisomies 18 and 21.Obstet Gynecol. 1999;93:869-72.  PUBMED
9. ACOG Practice Bulletin. Clinical Management Guidelines for Obstetrician-Gynecologists. Prenatal diagnosis of fetal chromosomal abnormalities.Obstet Gynecol. 2001;97(5 Pt 1):suppl 1-12.PUBMED
10. Trisomy 18 Syndrome. In: Jones, Kenneth Lyons, M.D. Smith's Recognizable Patterns of Human Malformations, Saunders Co: Philadelphia, 1997: 14-15.

Created: 12/26/2005