Characterizing the 'Pseudo-Septum' in Fetal MRI: Diagnostic Implications for Septal Agenesis | Chapter 5 | Medical Science: Trends and Innovations Vol. 5

Background: Septal agenesis (SA), which involves the partial or complete absence of the septum pellucidum, is a rare congenital anomaly, with a prevalence of approximately 2-3 per 100,000 live births. This anomaly can occur in isolation or as part of complex congenital malformations such as septo-optic dysplasia (SOD), holoprosencephaly, or corpus callosum agenesis. SA and the "pseudo-septum" phenomenon are rare midline abnormalities identified in fetal MRI, often posing diagnostic challenges. Accurate differentiation between true SA and pseudo-septum is critical for prenatal counseling and management. This study aims to characterize the imaging features of true SA and pseudo-septum in fetal MRI and analyze their association with other central nervous system (CNS) anomalies and postnatal outcomes.

Methods: A total of 79 fetuses with suspected midline anomalies underwent detailed MRI assessments at a tertiary care center in India. The presence of true SA and pseudo-septum was evaluated, along with associated findings like ventriculomegaly and corpus callosum agenesis. Diagnostic accuracy metrics for MRI were calculated using histopathological and clinical follow-up as gold standards. Statistical comparisons were performed to analyze associations between SA, pseudo-septum, and neurodevelopmental outcomes.

Results: True SA was confirmed in 29 cases (36.7%), while 21 cases (26.6%) were identified as pseudo-septum. Ventriculomegaly was more frequent in pseudo-septum cases compared to true SA (66.7% vs. 31.0%, OR: 4.2, p=0.004). The sensitivity and specificity of MRI for diagnosing SA were 81.0% and 69.2%, respectively, with an overall accuracy of 77.2%. Postnatal outcomes showed a trend toward higher rates of neurodevelopmental delay in true SA cases (31.0% vs. 9.5%, p=0.051), although this did not reach statistical significance.

Conclusion: This study highlights the diagnostic challenges posed by the pseudo-septum phenomenon in differentiating true SA. While fetal MRI remains a reliable tool, the presence of pseudo-septum and ventriculomegaly requires careful interpretation to avoid misdiagnosis. Enhanced imaging protocols and further research into the long-term outcomes of these conditions are essential to improve prenatal care and clinical management in resource-limited settings. Overall, these insights are essential for refining prenatal diagnostic strategies and improving the clinical management of fetal CNS anomalies.

 

Author (s) Details

 

Bhavya Kataria
Department of Radiodiagnosis, Anchal Health Care, Ghaziabad, Uttar Pradesh, India and Department of Radiodiagnosis, Atal Bihari Vajpayee Institute of Medical Sciences, Dr. Ram Manohar Lohia Hospital, D-12 Tower 1 Type 4 East Kidwai Nagar, New Delhi 110023, India.

 

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