Prenatal 2D/3D Ultrasound in Fetal Dural Sinus Malformations: Case Series and Prognostic Insights

To evaluate the benefit of three-dimensional (3D) ultrasound over two-dimensional (2D) imaging in diagnosing fetal dural sinus malformations (DSM) and to explore the correlation between sonographic features, such as thrombosis and sinus involvement, with perinatal and postnatal outcomes.

This retrospective case series included 8 fetuses diagnosed with DSM at our center from 2020 to 2025. All cases underwent 2D and 3D ultrasound, with findings correlated to perinatal and postnatal outcomes. A literature review was conducted using PubMed, Embase, and Web of Science, with keywords: "fetal dural sinus malformation," "prenatal ultrasound," and "3D ultrasound."

The median gestational age at diagnosis was 27 weeks (range 20-35). Lesions involved the torcular Herophili (4/8), torcular and superior sagittal sinus (2/8), superior sagittal sinus (1/8), and posterior fossa venous region (1/8). Associated anomalies included hydrocephalus, mild ventriculomegaly, fetal growth restriction (FGR), and pleural and peritoneal effusions. 2D ultrasound identified cystic or anechoic lesions (18 × 19 mm to 90 × 110 mm), with 62.5% showing thrombosis. 3D ultrasound enhanced lesion delineation, venous continuity, thrombus morphology, and confirmed the absence of arterialization. Genetic testing (cfDNA and/or CMA) was normal in all cases. Among the 8 pregnancies, two were terminated, one resulted in fetal demise, and five were liveborn. Four (50%) had favorable neurodevelopmental outcomes at 29-60 months.

Combined 2D/3D ultrasound improves prenatal DSM assessment, with key features, particularly thrombosis, correlating with adverse outcomes. 3D ultrasound should be integrated into routine diagnostic protocols.