Follow-up Study of 119 cases of Fetal Choroid Plexus Cysts in the Second Trimester: Associated with Trisomy 18?

Lee, Eun Hye; Lee, You Me; Shin, Myung Choel; Min, Yu Seon; Lee, Sang Hee; Kim, Hyeon Chul; Kim, Jong Wook; Lee, Sook Hwan; Lee, Wee Hyun; Cho, Jin Ho; Lee, Chung No; Lee, Kyu Hyung; Kim, Se Hyun

Abstract

OBJECTIVE
To evaluate the clinical significance of fetal choroid plexus cysts (CPCs) in the second trimester, especially an association with trisomy 18.
METHODS
From March 1998 through June 1999, second trimester screening ultrasonography was performed on 4,948 unselected single-ton pregnancies. CPCs were noted in 132 fetuses. Among them, detailed ultrasonography and follow-up was possible in 119 cases and they were recruited into the study. There were 91 cases of isolated CPCs and 28 cases of CPCs in high-risk population. "Isolated CPCs" were defined as: mother did not have any risk factors requiring amniocentesis and there were no other sonographic abnormalities on detailed ultrasound. "CPCs in high-risk population" were defined as: mother had any risk factor requiring karyotyping or there were any other sonographic abnormalities although she was general population. Amniocentesis was performed in 39 cases. We compared gestational age at time of detection, size, bilaterally, multiplicity, and complexity of CPCs in the group of isolated CPCs and CPCs in high-risk population (t-test, chi-square test; P<0.05). We evaluated the findings of detailed and follow-up ultrasonography, karyotypes, and final outcomes of pregnancy.
RESULTS
Gestational age at time of detection was not different in both groups of isolated CPCs and CPCs in high-risk population (19+/-2 vs 18+/-1 wk, p>0.05). Mean size (6.4 vs 6.2 mm), bilaterality (60% vs 57%), multiplicity (66% vs 57%), and complexity (8% vs 14%) of CPCs were also similar. All CPCs were disappeared irrespective of size and mean time of disappearance was 25+/-3 and 26+/-3 week, respectively (p>0.05). All cases of isolated CPCs resulted in phenotypically-normal neonates. It was confirmed by either amniocentesis or postnatal examination by the pediatrician. Among fetuses having CPCs in high-risk population, two trisomy 18 and one trisomy 21 were detected. All of them had positive result of maternal serum marker test and/or sonographic abnormalities. Remaining cases were proved normal.
CONCLUSION
The risk of chromosome abnormalities is very high when CPCs are associated with other abnormalities on detailed ultrasound, indicating a clear need to offering genetic amniocentesis. As contrast, the risk of chromosome abnormalities for a case of isolated CPCs is very low, and in this series there was no trisomy 18. Therefore isolated CPCs should be considered as the indication of detailed ultrasound examination, but not routine karyotyping.