Isolated choroid plexus cyst in low-risk women less than 35 years old

Objective: The purpose of this study was to determine the incidence of trisomy 18 in women who are <35 years old and who have sonographically detected isolated choroid plexus cyst. Study Design: A meta-analysis of prospective trials that were published in the English language between 1990 and 2000 was performed. Each trial met the following inclusion criteria: (1) prospective trial, (2) total population screened during the study period reported, (3) maternal age (either numeric or descriptive) reported, and (4) pregnancy/neonatal outcomes reported. An isolated choroid plexus cyst for the purpose of this study was defined as absence of sonographically detected structural abnormalities and normal serum analyte screens, if reported. Results: Eight trials met the criteria and were used for analysis. A total of 106,732 women were screened through articles that were published between 1990 and 2000. The total number of fetuses with choroid plexus cysts that were identified in second-trimester scans were 1235 (incidence, 1.2%). The incidence of isolated choroid plexus cysts in women who were <35 years old was 1.0% (n = 1017 women). There were no cases of trisomy 18 in women with isolated choroid plexus cyst who were <35 years old. Four structural abnormalities were noted on postnatal examination; all four neonates had normal karyotypes. Conclusion: There is no evidence that detection of isolated choroid plexus cyst in women who are <35 years of age increases the risk of trisomy 18. Therefore, amniocentesis is not warranted because of the inherent risk of pregnancy loss that is associated with the procedure. Better algorithms are needed to screen women who have a low risk for trisomy 18. (Am J Obstet Gynecol 2002;187:1246-9.)