Normal Anterior Fontanelle Appearance in a 7-Month-Old
The anterior fontanelle in a 7-month-old infant should be flat (level with the skull) when the infant is upright and calm. A flat fontanelle is the normal finding, while a full or bulging fontanelle is pathological and warrants immediate evaluation for increased intracranial pressure or other serious conditions 1.
Normal Fontanelle Characteristics
- The anterior fontanelle should be soft and flat when palpated with the infant in an upright position and at rest 2
- Normal anterior fontanelle pressure in term infants is approximately 10.2 ± 0.4 cm H₂O 3
- The median time of closure for the anterior fontanelle is 13.8 months, so at 7 months of age, the fontanelle should still be open but flat 2
Pathological Findings Requiring Evaluation
Bulging (Full) Fontanelle
A bulging or full anterior fontanelle is always abnormal and indicates:
- Increased intracranial pressure from conditions such as meningitis, intracranial hemorrhage, or hydrocephalus 1, 2
- Intracranial or extracranial tumors 2
- In the context of fever, meningitis must be excluded urgently 4
- Elevated fontanelle pressure (>13 cm H₂O in term infants suggests pathology) 3
Critical caveat: Other infections of the central nervous system or intracranial hemorrhage should be considered as alternative diagnoses in a child with a full fontanelle 1. A bulging fontanelle with fever mimicking meningitis can occasionally represent benign intracranial hypertension, but serious pathology must be ruled out first 4.
Sunken Fontanelle
- A sunken fontanelle usually indicates dehydration and requires assessment of hydration status 2
Clinical Assessment Approach
When examining the fontanelle:
- Palpate with the infant upright and calm (crying or lying flat can cause physiologic fullness) 2, 5
- Assess for pulsations (normal finding) 5
- Evaluate in conjunction with other clinical signs: altered mental status, neck stiffness, seizures, or abnormal neurological signs 1
- Consider imaging if abnormalities are detected: ultrasound through the open fontanelle is the preferred initial modality without radiation exposure 6, 7
Bottom line: A flat fontanelle is normal at 7 months; any fullness or bulging requires urgent evaluation for increased intracranial pressure or infection 1, 2.