Longitudinal Outcomes of Fetuses with an Isolated Narrow Cavum Septi Pellucidi: Prenatal Diagnosis to Early Childhood Neurodevelopment Assessment.

OBJECTIVES: To evaluate prenatal and postnatal immediate and long-term outcomes of fetuses with an isolated narrow cavum septi pellucidi(CSP). METHODS: Single-centre retrospective review of a cohort of fetuses with an isolated narrow CSP (below -2 standard deviations [SD] for gestational age [GA]) identified on mid-trimester anomaly scan from 2017-2022. RESULTS: During 6 years, 77546 pregnant women underwent anomaly scan, and 228 were identified with an isolated narrow CSP. A follow-up ultrasound at a mean GA of 28.9 weeks showed that CSP measurements were normalized in 58.5% of cases, while in the remaining cases, they were below -2 SD for the respective GA. There were no additional cerebral findings; however, three fetuses were growth-restricted. Among these, 130 mothers delivered at our institution, at a mean GA of 38.3 weeks, and were followed for perinatal and long-term neurodevelopmental outcomes. Clinical examination at birth was unremarkable for all neonates. For the majority of them (n=105/130), cranial scan at one month was normal, and minor findings were noted in 18 cases. Neurodevelopmental outcomes were normal for 81.5% (n=106) of infants at 2 years, while 24 (18.5%) were referred to the Child Development Unit with concerns regarding speech and language delay, behavioral issues, gross motor delay, and global developmental delay. Extended follow-up showed normal outcomes for 89.2%(n=116) of cases; nine of 15 children with speech-language delay had improved, while five (3.85%) were diagnosed with autism spectrum disorder. CONCLUSION: An isolated narrow CSP is a benign, transitory, subtle anatomical finding in the prenatal brain. However, its identification should prompt detailed neuroimaging and evaluation to exclude associated abnormalities. The long-term neurodevelopmental outcome is overall good when the finding is isolated.