Anencephaly in Newborns: Clinical Presentation, Diagnostic Features, and Management

Anencephaly is one of the most severe neural tube defects compatible with life until birth, characterized by the absence of a major portion of the brain, skull, and scalp. The image depicts an anencephalic newborn in profile view, illustrating the distinctive craniofacial features associated with this condition. Anencephaly results from failure of the rostral (head) end of the neural tube to close during embryonic development, typically between the 23rd and 26th day of gestation. This devastating congenital anomaly is universally fatal, with most affected newborns surviving only hours to days after birth. Understanding the characteristic physical manifestations, underlying pathophysiology, and available management options is essential for healthcare professionals involved in perinatal and neonatal care.

Visible Anatomical Features in the Anencephalic Newborn

The image does not contain specific labels, but several characteristic anatomical features of anencephaly are visible:

Absent Cranial Vault: The most striking feature is the complete absence of the calvarium (skull cap). This allows visualization of the rudimentary neural tissue that would normally develop into the cerebral hemispheres. The absence of proper skull formation is a direct consequence of the neural tube closure defect.

Exposed Neural Tissue: Though not prominently visible in this particular image, anencephalic newborns typically have exposed neural tissue at the crown of the head. This tissue appears as a vascular, spongy mass and represents rudimentary brain structures that failed to develop properly.

Prominent Eyes: The eyes appear somewhat bulging or prominent. This occurs because the normal orbital roof is malformed or absent, creating the characteristic “frog-like” appearance often described in clinical settings. Despite this abnormal appearance, the eyes themselves may be structurally normal.

Craniofacial Profile: The profile shows a distinctive sloping of the forehead and lack of proper cranial development above the orbital ridges. This results in the characteristic facial appearance sometimes described as having a “frog-like” appearance with a flattened or absent forehead.

Ears: The ear structure appears relatively normal in this image, though low-set ears are common in anencephalic newborns due to overall disruption of craniofacial development.

Pathophysiology and Embryology of Anencephaly

Anencephaly represents a profound failure in early embryonic development. The essential disruption occurs during neural tube formation, the process that gives rise to the brain and spinal cord. Under normal circumstances, the neural tube closes completely by day 28 of gestation. The fundamental mechanism responsible for anencephaly involves the following sequence:

During the third and fourth weeks of embryonic development, the neural plate folds to form the neural tube. This process, known as neurulation, begins in the middle of the embryo and proceeds bidirectionally toward both the cranial and caudal ends. In anencephaly, the cranial end of the neural tube fails to close properly, preventing normal development of the forebrain and the formation of the protective calvarium.

The prosencephalon (forebrain) and mesencephalon (midbrain) are most severely affected, while the rhombencephalon (hindbrain) may be partially preserved. This pattern explains why basic brainstem functions like cardiac and respiratory regulation may be present despite the absence of higher brain structures. The embryological failure also disrupts the formation of overlying structures, including the meninges, skull, and scalp.

Genetic and Environmental Risk Factors

Multiple factors contribute to the development of anencephaly, highlighting the complex interplay between genetic predisposition and environmental influences:

• Folate Deficiency: Inadequate maternal folic acid intake represents the most significant modifiable risk factor. Neural tube closure requires folate-dependent metabolic pathways, with deficiency increasing risk by 2-8 times.
• Genetic Factors: Several genetic variants affecting folate metabolism increase susceptibility, particularly mutations in the MTHFR gene (methylenetetrahydrofolate reductase). Family history of neural tube defects raises recurrence risk to approximately 3-5%.
• Maternal Conditions: Pre-gestational diabetes mellitus, obesity, and hyperthermia during early pregnancy correlate with increased risk. Maternal diabetes is associated with a 2-10 fold increased risk of all neural tube defects.
• Teratogenic Medications: Certain anticonvulsants, particularly valproic acid, significantly increase risk through interference with folate metabolism and direct toxic effects on developing neural tissue.

Prenatal Diagnosis and Screening

Modern prenatal care has dramatically improved early detection of anencephaly. Several complementary approaches enable diagnosis:

Maternal Serum Alpha-Fetoprotein (MSAFP)

Elevated levels of alpha-fetoprotein in maternal serum strongly suggest open neural tube defects. This screening test is typically performed between 15-20 weeks of gestation. In anencephaly, MSAFP levels are markedly elevated, often exceeding 4.0 multiples of the median (MoM). The absence of the protective skull allows fetal proteins to leak into the amniotic fluid and subsequently into maternal circulation.

Ultrasound Examination

Anencephaly can be reliably diagnosed by ultrasound as early as 11-14 weeks of gestation, with nearly 100% sensitivity by the second trimester. Characteristic sonographic findings include:

• Absence of the cranial vault above the orbits
• Exposed neural tissue with the “frog eye” sign
• Abnormal facial profile with absent forehead
• Polyhydramnios (excess amniotic fluid) in later pregnancy

Three-dimensional ultrasound provides enhanced visualization of the defect and may assist in counseling parents about the nature and severity of the malformation.

Fetal MRI

In complex cases or when additional anomalies are suspected, fetal MRI may provide complementary information about central nervous system development. This advanced imaging technique can more precisely characterize the extent of brain abnormalities and detect associated malformations that might influence clinical management.

Clinical Management and Ethical Considerations

The universally fatal nature of anencephaly presents unique challenges in clinical management. Several approaches must be considered:

Obstetric Management

When anencephaly is diagnosed prenatally, healthcare providers must compassionately discuss several management options with the family:

• Pregnancy termination, depending on gestational age and local regulations
• Continuation of pregnancy with standard obstetric care
• Continuation of pregnancy with palliative care planning for the neonate

If the pregnancy continues, vaginal delivery is typically recommended, as cesarean delivery offers no benefit to the fetus and increases maternal morbidity. However, the abnormal head shape may occasionally complicate vaginal delivery, requiring careful obstetric management.

Neonatal Palliative Care

For live-born anencephalic infants, the focus shifts to palliative care. This approach emphasizes:

• Comfort measures to minimize suffering
• Family-centered care that honors parental wishes
• Support for skin-to-skin contact and bonding
• Pain management as needed
• Dignified end-of-life care

Most anencephalic newborns survive only hours to days, though rare cases of survival for weeks or months have been reported. Throughout this time, the medical team must provide ongoing support to the family while managing the infant’s basic needs.

Organ Donation Considerations

Some families may explore organ donation from anencephalic infants. This presents complex ethical and practical challenges:

• The dead donor rule requires declaration of death before organ procurement
• Anencephalic infants may have functioning brainstems, complicating brain death determination
• Protocols exist in some regions for donation after cardiac death
• Technical challenges include organ size matching and quality preservation

Medical teams must navigate these considerations with sensitivity while upholding ethical standards and respecting family wishes.

Prevention Strategies

The most effective intervention for neural tube defects is primary prevention through periconceptional folic acid supplementation. Public health initiatives include:

• Daily supplementation with 400-800 μg of folic acid for all women of childbearing potential
• Higher doses (4 mg daily) for women with prior neural tube defect-affected pregnancies
• Food fortification programs adding folic acid to grain products
• Enhanced supplementation for women taking medications that interfere with folate metabolism

These measures have dramatically reduced the incidence of neural tube defects, with studies demonstrating up to 70% reduction following implementation of folic acid fortification programs. This success emphasizes the critical importance of preconception care and counseling.

Support for Families

Families facing an anencephaly diagnosis require comprehensive psychological support through the diagnostic, decision-making, and bereavement processes. Key support components include:

• Accurate, sensitive communication about the diagnosis and prognosis
• Non-directive counseling about available options
• Perinatal hospice support for families continuing pregnancy
• Bereavement services and memory-making opportunities
• Connection with support groups of families with similar experiences
• Long-term follow-up to address grief and facilitate healing

The psychological impact of anencephaly extends beyond the immediate family to include extended family members and healthcare providers, necessitating a comprehensive support system.

1. Anencephaly: Clinical Features, Diagnostic Criteria, and Management Options for Medical Professionals
2. Comprehensive Guide to Anencephalic Disorders: Embryology, Diagnosis, and Ethical Considerations
3. Neural Tube Defects: Understanding the Clinical Presentation and Management of Anencephaly
4. Anencephalic Newborns: Pathophysiology, Prenatal Detection, and Palliative Care Approaches
5. Congenital Anencephaly: Essential Knowledge for Perinatal and Neonatal Care Providers