Careful planning of research with all clinic and DR staff will be necessary for successful execution of the NCS or other large-scale clinical research studies.

Objectives: Subependymal pseudocysts (SEPC) are increasingly detected during routine fetal ultrasound scanning. Our purpose was to determine the proportion of apparently isolated SEPC with underlying pathologies and the features that may indicate the need for further investigations. Methods: A retrospective study was conducted on 21 patients. Fetal MR Imaging and amniocentesis for karyotyping, comparative genomic hybridisation and CMV-PCR were systematically proposed for each patient. Results: The mean gestational age at diagnosis was 30 weeks. The cases were divided into apparently isolated SEPC (group A,n=18) and those with additional findings such as white matter signal anomalies or polymicrogyria (group B, n=3). Amniocentesis was performed in 48% of cases. Fetal brain MRI was performed in 76%. The inferior wall of the frontal horns was the main location in both groups. There was no difference in size, number or laterality between the two groups. All cases in group A had a normal neonatal outcome including a case of congenital CMV infection. In group B, 3 infants had metabolic diseases and poor neonatal outcomes, 2 cases of pyruvate carboxylase deficiency and 1 case of pyruvate dehydrogenase deficiency. Conclusions: SEPC should be considered as a warning sign for associated pathologies. Family history and further investigations should be considered to confirm the isolated nature of SEPC.