Choroid plexus cyst revisited – the KK Hospital experience

Objective:  To study the clinical outcome of cases of choroid plexus cysts (CPC), the prognostic factors that increase the risk of aneuploidy and to formulate a counseling strategy for CPC.Study design:  Cases of CPC detected at screening ultrasonography (between 18 and 24 weeks gestation) from 1 October 1996 to 30 September 2000 in low risk antenatal patients at KK Women's & Children's Hospital, Singapore, were studied. The risk of aneuploidy and postnatal cranial ultrasonography of the cases were analyzed. Data was stratified according to maternal age, size of CPC, unilaterality or bilaterality and presence of concomitant structural abnormalities and/or ultrasound markers (non‐isolated).Results:  There were 485 cases with CPC among 56 746 patients (incidence 0.08%). Overall risk of aneuploidy was 6.2%. There were 30 cases of chromosomal abnormalities including 23 cases of trisomy 18; five cases of trisomy 21; one case of monosomy X and one case of Klinefelter syndrome. Cases of non‐isolated CPC were at significantly higher risk for aneuploidy (56.8%) compared to isolated CPC (1.4%), P < 0.001. No significant difference in risk was detected between unilateral and bilateral isolated CPC (P = 0.4), and with increasing size of isolated CPC. A near significant increase in risk was found between the under‐30 age group (0.37%) and the above‐30 age group. (2.3%) (P = 0.07). In non‐isolated CPC, the risk of aneuploidy ranged from 14.3% at age 20–24 and 100% at age 41–45. Likelihood ratio for trisomy 18 was 7.2 for isolated CPC, 1276 for non‐isolated CPC and 0.54 for absent CPC in the whole scanned population.Conclusion and recommendations:  Our results support the need for a thorough ultrasound anatomic survey for all cases of diagnosed CPC. Karyotyping should be offered to all cases of non‐isolated CPC. In isolated CPC, there may be benefit from offering karyotyping when maternal age exceeds 30.