Second trimester neurosonography.

Congenital malformations of the central nervous system (CNS) are among the most common congenital anomalies, with neural tube defects being the most prevalent, comprising approximately 40% of CNS malformations. The estimated prevalence of CNS anomalies varies, but many cases remain undiagnosed at birth, potentially leading to underestimation. These conditions significantly impact neurodevelopmental outcomes and contribute to a high societal burden due to the need for specialized medical care and support. Prenatal imaging plays a crucial role in the early detection of CNS anomalies. Routine mid-trimester ultrasound, performed between 18 and 24 weeks of gestation, is the primary screening method, with detection rates ranging from 68% to 92%. Standardized guidelines by the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) recommend acquiring three axial planes-transventricular, transthalamic, and transcerebellar-to improve diagnostic accuracy. The addition of mid-sagittal plane evaluation may further enhance detection rates. When abnormalities are suspected, targeted fetal neurosonography (with transvaginal probes), incorporating coronal and sagittal planes, is necessary for detailed assessment and diagnosis. Accurate prenatal assessment of CNS anomalies is critical for diagnosis, prognosis, and management planning. Standardized approaches and advanced imaging techniques contribute to improved detection and better-informed clinical decision-making, ultimately enhancing outcomes for affected fetuses.