EP05.69: Early prenatal detection of Arnold‐Chiari type II malformation: insights from a diagnostic case study

Arnold Chiari malformation type II (ACM-II) is a rare congenital anomaly characterised by herniation of the cerebellar vermis and brainstem through the foramen magnum. Prenatal diagnosis of ACM-II is crucial for appropriate counselling and management. This case report aims to illustrate an ACM-II detected on an early second trimester appointment ultrasound, emphasising the significance of early recognition and prenatal counselling. We report a case of a 38-year-old, 2G1P, in whom ultrasound findings were suggestive of ACM-II. Subsequent consultation confirmed the presence of myelomeningocele, the “lemon” sign, ventriculomegaly, and a “banana-shaped” cerebellum. The parents were provided with comprehensive counselling regarding the prognosis and potential complications associated. Their informed decision was to undergo amniocentesis and then opt for termination of pregnancy. ACM-II typically presents with myelomeningocele, hindbrain herniation, and associated central nervous system anomalies. Early diagnosis allows for timely interventions and appropriate prenatal counselling. Management strategies may include neurosurgical interventions postnatally to prevent neurological sequelae. Early detection of ACM-II through ultrasound facilitated parental decision-making and highlighted the importance of advanced imaging in prenatal care. This case contributes to the existing literature by illustrating the benefits of early diagnosis but also calls for continued research into optimising management for ACM-II and similar prenatal conditions. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.