Choroid plexus cysts: Is biochemical testing a valuable adjunct to targeted ultrasonography?

OBJECTIVE: We sought to determine whether biochemical testing is a valuable adjunct to ultrasonography in selecting patients with fetal choroid plexus cysts for amniocentesis. STUDY DESIGN: The study population consists of 128 patients who had fetal c horoid plexus cysts detected during ultrasonography performed between 18 an d 22 weeks' gestation. The patients had genetic counseling, and amniocentes is and biochemical testing were offered to all patients. The data were anal yzed by dividing the patients into 3 groups. Group 1 had targeted ultrasono graphy only, group 2 had ultrasonography and maternal serum alpha-fetoprote in testing, and group 3 had ultrasonography and triple-screen (maternal ser um alpha-fetoprotein, human chorionic gonadotropin, and estriol) testing. O utcome was determined by fetal karyotype or by neonatal examination by a pe diatrician for patients who declined amniocentesis. RESULTS: There were 25 patients in group 1. Isolated choroid plexus cysts w ere detected in 20 fetuses, and all had normal outcomes. Additional anomali es were detected in 5 fetuses. Two had normal karyotypes, and 3 had trisomy 18. There were 52 patients in group 2. The maternal serum alpha-fetoprotei n levels were normal in 44 patients, 41 of whom had isolated fetal choroid plexus cysts. Of these 44 patients, 40 had normal out comes, and 1 patient had a fetus with trisomy 18. The remaining 3 patients with normal maternal serum alpha-fetoprotein levels had additional fetal anomalies on ultrasonog raphy, but the karyotypes were normal. The maternal serum ol-fetoprotein le vels were abnormal in 8 patients, of whom 6 had fetuses with isolated choro id plexus cysts and normal karyotypes. Two patients had additional fetal an omalies detected on ultrasonography and had abnormal karyotypes, 1 with tri somy 21 and 1 with trisomy 18. There were 51 patients in group 3. Results o f the triple screen were normal in 32 patients. The choroid plexus cysts we re isolated in 29 of the 32 patients, and all 29 fetuses had normal karyoty pes. The other 3 patients with normal triple-screen results had additional fetal anomalies on ultrasonography. One fetus had normal chromosomes, and 2 had trisomy 18. The remaining 19 patients had abnormal triple-screen resul ts. Among them, 16 fetuses had isolated choroid plexus cysts, 13 of whom we re normal. 2 had trisomy 18, and 2 had a de novo unbalanced translocation. The remaining 3 fetuses had additional anomalies, and all 3 fetuses had tri somy 18. There were 14 fetuses with significant chromosomal abnormalities. Nine mothers were <35 years old, and 5 were greater than or equal to 35 yea rs old. CONCLUSIONS: This study shows the following: (1) The triple screen is a use ful adjunct to targeted ultrasonography in selecting patients with fetal ch oroid plexus cysts for amniocentesis. (2) A normal triple-screen result and the absence of additional fetal anomalies on ultrasonography reliably excl ude an underlying chromosomal abnormality and amniocentesis is not indicate d. (3) If the triple-screen result is abnormal, additional anomalies are se en on ultrasonography, or the mother is aged greater than or equal to 35 ye ars, then fetal karyotyping is recommended. (4) Patients who decline fetal karyotyping should have follow-up ultrasonography in 34 weeks' time.