Diagnostic Performance of Fetal Brain Ultrasound for Prenatal Detection of Fetal Meningitis: A Systematic Review

Abstract

Background: Fetal meningitis and congenital central nervous system (CNS) infections are associated with significant neurological morbidity, including ventriculomegaly, hydrocephalus, developmental delay, hearing impairment, and long-term neurodevelopmental deficits. Early prenatal diagnosis is challenging because clinical manifestations are often absent and laboratory confirmation may be difficult. Fetal brain ultrasound, particularly dedicated neurosonography, plays a central role in the prenatal assessment of suspected CNS infections.

Objective: To evaluate the diagnostic performance of fetal brain ultrasound in the prenatal detection of fetal meningitis and related congenital CNS infections.

Methods: A systematic literature search was conducted in PubMed and Google Scholar. Studies reporting prenatal ultrasound findings in fetuses with suspected or confirmed CNS infection were included. After screening and eligibility assessment, 12 studies met the inclusion criteria and were included in the qualitative synthesis. Due to heterogeneity in study design, imaging protocols, and outcome measures, a meta-analysis was not performed. Study quality was assessed using the QUADAS-2 tool.

Results: The included studies consisted of prospective cohorts, retrospective analyses, case series, and observational studies, with sample sizes ranging from 5 to 250 participants. The most frequently reported sonographic findings were ventriculomegaly, periventricular echogenicity, intracranial calcifications, ventricular debris, and hydrocephalus. Ultrasound demonstrated high sensitivity for detecting major structural abnormalities associated with fetal CNS infection, particularly ventricular abnormalities and intracranial inflammatory changes. However, its sensitivity was lower for subtle cortical abnormalities, white matter lesions, and migrational disorders. Fetal MRI provided complementary diagnostic information and improved detection of parenchymal, cortical, cerebellar, and posterior fossa abnormalities. Quality assessment revealed an overall moderate risk of bias, primarily due to small sample sizes, retrospective study designs, and variability in imaging protocols.

Conclusion: Fetal brain ultrasound remains an effective and indispensable first-line imaging modality for the prenatal detection of abnormalities associated with fetal meningitis and congenital CNS infections. Dedicated neurosonography enhances diagnostic accuracy, while fetal MRI serves as a valuable complementary tool for identifying subtle brain abnormalities and improving prognostic evaluation. Further prospective studies are needed to establish standardized imaging criteria and determine the true diagnostic accuracy of prenatal ultrasound for fetal meningitis.