Bilateral choroid plexus cysts: What causes CPC's?

I am 20 weeks pregnant and my baby may have bilateral choroid plexus cysts. A second ultrasound is scheduled. What causes CPCs and what are potential effects on the baby when CPCs have disappeared and when they have not?


Peg Plumbo CNM

Peg Plumbo has been a certified nurse-midwife (CNM) since 1976. She has assisted at over 1,000 births and currently teaches in the... Read more

These type of cysts can be a normal phenomenon and can regress spontaneously. I have received many letters from mothers who had such a diagnosis and worried their entire pregnancies or until another ultrasound showed resolution.

The incidence of these cysts seems to be about one percent. Some seem to be associated with genetic problems such as trisomy 18 and can be a marker for other types of chromosomal problems. Some authors do not recommend amniocentesis, but feel it should be offered. Because these cysts often resolve, many unnecessary amnios would be done if they were performed in all of these cases. Ultrasound can detect other markers and signs such as "nuchal (neck) thickness," which is more indicative of a trisomy problem. If there are accompanying indications in addition to the cysts, then the benefits of amniocentesis may well outweigh the risks.

I hope these resolve and you are freed from the intense anxiety this causes. Good luck.

Below you will find some information from a search I did for you on this topic.

Medline Abstracts

Burrows A. Ramsden GH. Frazer MI.
Choroid plexus cysts in the fetal brain [see comments].
Comment in: Aust N Z J Obstet Gynaecol 1994 May;34(2):220, Comment in: Aust N Z J Obstet Gynaecol 1994 May;34(2):221
Australian & New Zealand Journal of Obstetrics & Gynaecology. 33(3):262-4, 1993 Aug.
Choroid plexus cysts may be detected in the fetal choroid plexus on routine second trimester ultrasound scanning. The presence of these cysts is associated with trisomy 18 (Edward syndrome) in 3.47 percent of cases and with trisomy 21 (Down syndrome) in 0.46 percent of cases. The cysts themselves almost always disappear by 23 weeks and are thought to be a normal developmental variant. The world literature experience would indicate that the size of the choroid plexus cyst and the presence of bilateral cysts has no bearing on the magnitude of risk of chromosomal abnormality; 76 percent of babies with trisomy 18 also have other dysmorphic features which may be detectable by ultrasound. It is strongly advised that genetic counselling be undertaken and amniocentesis be considered when choroid plexus cysts are identified in the fetus.

Kennedy KA. Carey JC.
Choroid plexus cysts: significance and current management practices.
Seminars in Ultrasound, CT & MRI. 14(1):23-30, 1993 Feb.
Choroid plexus cysts are commonly found in normal fetuses in the second trimester, but the presence of cysts is an indication for a targeted ultrasound scan for signs associated with aneuploidy. In this review, the authors explain the histological basis for choroid plexus cyst formation, the association with aneuploidy, and the management controversies that continue to be debated in the literature.
Rebaud A. Chardon C. Rebaud MF. Berland M.
[Prenatal screening for cysts of choroid plexus. Evolution and interpretation of 30 cases]. [Review] [French]
Journal de Gynecologie, Obstetrique et Biologie de la Reproduction. 21(6):665-70, 1992.
The authors report 30 cases in which they diagnosed a cyst of the choroid plexus antenatally between the 18th and the 36th week of amenorrhoea (mean 21 weeks). Choroid plexus cysts show up in some pictures as round or oval cysts clearly visible in the region of the choroid plexus. They appear in the lateral cerebral ventricles. They frequently occur between the 15th and 25th week of amenorrhoea (0.6 to 2.5 percent of pregnancies), unilaterally or bilaterally (46 percent) either on the right of left side and varying in size (three to 20 mm). These characteristics do not influence the way they evolve. If a single choroid plexus cyst is found, a control ultrasound should be carried out four weeks later. Ninety-six percent of them have disappeared by the end of the second trimester; but if they do persist in the third trimester (4 percent) they are not necessarily pathological. On the other hand, if a choroid plexus cyst is associated with some other morphological biometric abnormality, antenatal chromosome testing should be carried out because trisomy 18 is more common in this situation (4.8 percent) than in the general population. [References: 19]

Perpignano MC. Cohen HL. Klein VR. Mandel FS. Streltzoff J. Chervenak FA. Goldman MA.
Fetal choroid plexus cysts: beware the smaller cyst.
Radiology. 182(3):715-7, 1992 Mar.
Current literature suggests that amniocentesis be performed on fetuses with simple choroid plexus cysts only when such cysts are 1.0 cm or greater in diameter and bilateral. At retrospective analysis of 3,769 patients, choroid plexus cysts were noted in 87 (2.3 percent), representing a rate three times greater than that of previous reports. Eight-three patients underwent amniocentesis. Six (7.2 percent) had abnormal karyotypes. Four patients had the commonly associated chromosomal abnormality trisomy 18. Two had karyotypes not usually associated with this problem: mosaic Turner syndrome and trisomy 21. Of the six patients with abnormal karyotypes, one had a four-mm-diameter unilateral choroid plexus cyst and three had bilateral cysts of three to five mm. Only one patient with a 16-mm cyst had any associated structural abnormality discovered at rigorous ultrasound examination. Karyotyping may be necessary in fetuses with small choroid plexus cysts. Deciding which patients should be encouraged to undergo amniocentesis is made more complex by these data.
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