Is the presence of isolated choroid plexus cyst(s) an indication for amniocentesis?

OBJECTIVE: Our purpose was to evaluate the risk of chromosomal abnormalities (especially trisomy 18) with isolated choroid plexus cyst(s) (CPC) detected by ultrasound at 18 to 20 weeks gestation. STUDY: During a 10-year period, 57 patients were found with isolated CPC on routine obstetric ultrasound. Amniocenteses were done in 36 patients. Presence of bilateral versus unilateral cysts was noted as was evaluation for other anomalies on advanced level ultrasound examination. RESULTS: Trisomy 18 was found in 3 of the 57 patients with CPC (bilateral in each case). In our study the risk of trisomy 18 was found to be 13.6% in the 22 isolated bilateral CPC. Two of 57 patients had rnild renal dilatation on ultrasound which disappeared 4 weeks later. These 2 patients also had bilateral CPC. No chromosomal anomaly or trisomy 18 was seen with isolated unilateral CPC. Other than the 3 trisomy 18, no pregnancies showed evidence of aneuploidy at amniocentesis or an anomaly at birth. The complication rates, Apgar scores, and pregnancy outcomes seemed to be normal in the pregnancies with CPC but no trisomy 18. CONCLUSION: The necessity of obtaining a karyotype for all fetuses with isolated CPC remains controversial. In our study the ratio of trisomy 18 in isolated bilateral CPC is 13.6% and this ratio is higher than pregnancy loss after amniocentesis (1/200) and the general risk for aneuploidy (1/260). These findings indicate that amniocentesis should be offered in the presence of isolated bilateral CPC. As we could not find anomalies, karyotyping may not be necessary in fetuses with isolated unilateral CPC. The presence of isolated CPC does not affect the route of deliver)' and pregnancy outcomes.