How is Anencephaly diagnosed?

Anencephaly is primarily diagnosed prenatally through routine obstetric ultrasound imaging, which identifies the absence of major portions of the brain and skull. Following birth, a physical examination by a neonatologist or pediatrician confirms the clinical presentation, as there is currently no curative treatment for this neural tube defect.

How is Anencephaly diagnosed during pregnancy?

The diagnostic process for Anencephaly typically begins during routine prenatal screening. Most cases are identified via a fetal ultrasound between 11 and 14 weeks of gestation, or during the detailed anatomical survey at 18 to 20 weeks. If Anencephaly is suspected, physicians may use the following diagnostic tools:

• High-resolution ultrasound: The primary tool to visualize the absence of the cranial vault and cerebral hemispheres.


• Maternal Serum Alpha-Fetoprotein (MSAFP) screening: Often elevated in blood tests when a neural tube defect is present.


• Fetal MRI: Occasionally used to confirm the diagnosis or rule out other structural abnormalities.

Which specialists are involved in the diagnosis of Anencephaly?

The diagnosis is usually made by an Obstetrician or a Maternal-Fetal Medicine (MFM) specialist. Following birth, a neonatologist or a pediatric neurologist will perform a physical assessment to confirm the diagnosis of Anencephaly. Because this is a devastating diagnosis, patients often benefit from the support of a genetic counselor to discuss the recurrence risk for future pregnancies and a palliative care team to provide compassionate support.

What is the differential diagnosis for Anencephaly?

While Anencephaly has a distinct clinical presentation, it must be differentiated from other conditions involving cranial defects. These include acrania (where the skull is absent but brain tissue is present), encephalocele, and severe microcephaly. Seeking a specialist, such as a perinatologist, is essential to ensure an accurate diagnosis, as these conditions have different clinical implications and prognoses.

Why is the diagnostic process so difficult for families?

Receiving a diagnosis of Anencephaly is a traumatic experience. Unlike many rare diseases that involve a "diagnostic odyssey" of years, Anencephaly is often identified quickly, but the suddenness of this news can feel overwhelming. At DiseaseMaps.org, 31 community members have shared their experiences, highlighting the vital importance of seeking specialized fetal medicine experts who can provide clear, compassionate communication during such a difficult time.

Next steps

• Consult with a Maternal-Fetal Medicine (MFM) specialist for a formal assessment.


• Speak with a genetic counselor to understand the underlying causes and recurrence risks.


• Connect with the 31 members at DiseaseMaps.org who have navigated this journey to find peer support.


• Prioritize palliative care and bereavement support services to help navigate the emotional impact of an Anencephaly diagnosis.

Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Anencephaly.


• Orphanet: Neural tube defect, anencephaly.


• Centers for Disease Control and Prevention (CDC): Facts about Anencephaly.


• OMIM (Online Mendelian Inheritance in Man): Anencephaly entry #206500.