Association of fetal choroid plexus cysts with trisomy 18 in a population previously screened by nuchal translucency thickness measurement.
OBJECTIVE
The study's aim was to determine any association between choroid plexus cysts (CPCs) and trisomy 18 in a population of fetuses previously screened by nuchal translucency (NT) thickness measurement.


METHODS
During the study period (May 1999 to December 2004), 7,795 fetuses had an NT scan and second-trimester fetal anatomical scan at our institution. The prevalence of trisomy 18 was determined among four types of pregnancies: 1) those with isolated CPCs, 2) those with CPCs and enlarged NT, 3) those with CPCs and other ultrasound markers, and 4) those with CPCs, enlarged NT, and other ultrasound markers. The fetal outcome according to NT and presence of CPCs was calculated. Incidence rates of enlarged NT and CPCs in fetuses with trisomy 18 and fetuses with normal chromosomes were also evaluated.


RESULTS
For the entire population, ten trisomy 18 cases were diagnosed prenatally (prevalence, 0.13%). Among fetuses with enlarged NT, the likelihood ratio of trisomy 18 was significantly increased in fetuses with CPCs compared with fetuses without such cysts (333.6 versus 15.2, P = .002). However, among fetuses with normal NT, no significant difference was demonstrated for likelihood ratio of trisomy 18 between fetuses with and without CPCs.


CONCLUSIONS
In pregnancies complicated by isolated CPCs, fetal karyotyping is not indicated when no additional anomaly is detected on ultrasonographic examination and first-trimester NT results are normal.
Cheng
Po-Jen
PJ
Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan, ROC. pjcheng@cgmh.org.tw
Shaw
Sheng-Wen
SW
Soong
Yung-Kuei
YK
D000293:Adolescent; D000328:Adult; D001927:Brain Diseases / Q000235:genetics*; D002831:Choroid Plexus; D002887:Chromosomes, Human, Pair 18; D003430:Cross-Sectional Studies; D003560:Cysts / Q000235:genetics*; D005260:Female; D006801:Humans; D007621:Karyotyping; D008875:Middle Aged; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D015995:Prevalence; D014314:Trisomy