Prenatal Chiari II Malformation with Spina Bifida and Associated Fetal Anomalies: A Case Report
Abstract
Background: Chiari II malformation (CM-II) is a complex developmental abnormality of the posterior fossa and hindbrain that is strongly associated with spinal dysraphism, particularly myelomeningocele. Prenatal ultrasonography plays a central role in its detection through recognition of characteristic cranial and spinal abnormalities. Associated anomalies may substantially influence prognosis and pregnancy management. Case report: A 25-year-old second gravida of gestation was referred for detailed fetal assessment at 19 weeks following the detection of multiple suspected structural abnormalities on routine ultrasonography (US). Patient had a previous history of spontaneous abortion approximately 8 months earlier. The current pregnancy was conceived spontaneously. There was no reported history of diabetes mellitus, hypertension, epilepsy, renal disease, significant medication exposure, or a family history of neural tube defects. Detailed US demonstrated a posterior spinal defect with an associated cystic sac, consistent with spina bifida and spinal meningocele. The fetal posterior fossa was abnormal, with a curved, banana-shaped cerebellum, effacement of the cisterna magna and caudal displacement of the hindbrain, findings suggestive of CM-II. Severe oligohydramnios, relatively small fetal thoracic dimensions with suspected pulmonary hypoplasia, bilateral increased renal parenchymal echogenicity, and non-visualization of the urinary bladder were also observed. Conclusion: This case highlights the importance of systematic second-trimester assessment of the fetal brain, posterior fossa, spine and genitourinary system when a neural tube defect is suspected. The coexistence of CM-II, spinal dysraphism, severe oligohydramnios, suspected pulmonary hypoplasia and bilateral echogenic kidneys represents a complex fetal abnormality with potentially significant prognostic implications. Recognition of these findings allows timely referral for multidisciplinary assessment and individualized parental counseling. BJusg. vol. 26, no. 2, December 2025, Page: 62-64