EP05.30: Atypical appearance of fetal brain vesicles a marker for early diagnosis of fetal acrania

In this case series, we present nine cases of acrania detected below 10 weeks of gestation from two tertiary ultrasound units. Acrania-anencephaly is a fatal neural tube defect believed to be caused by 17 to 28 days of incomplete cranial neurulation after fertilisation, in which the cranial part of the neural tube fails to close. The well-established first trimester ultrasound markers include the absence of calvarian bones along with varying amounts of disorganised brain tissue. At 7 weeks (CRL 9–14 mm), on high-resolution endovaginal ultrasound, the hypoechogenic brain vesicles or cavities can be identified, including the separated small and round lateral ventricles. By 9 weeks (CRL 23–31 mm), the size of the lateral ventricles increases rapidly. They are best seen in the parasagittal plane, where the C-shape becomes apparent. The inability to visualise or the presence of abnormal cystic formations in these vesicles or lateral ventricles may serve as early indicators of acrania, as evidenced by this case series (see figure 1). Most parents, when faced with a diagnosis of acrania, would opt to terminate the pregnancy, which is safer and less traumatic if done earlier in pregnancy. Thus, there is a strong emphasis on early diagnosis. In conclusion, identifying the early signs of acrania might lead to an early diagnosis. However, confirmation of the condition with a follow-up scan remains essential for providing appropriate counselling and aiding parental decision-making, even in cases of early diagnosis. 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.