Anterior fontanelle hydration status is assessed by examining its contour; which statement is true?

• A. Sunken fontanelle indicates dehydration; bulging indicates overhydration.
• B. Fontanelle status is not related to hydration.
• C. Bulging fontanelle indicates dehydration.
• D. Sunken fontanelle indicates overhydration.

Answer: (A)

Fontanelle contour in infants reflects fluid status. A sunken fontanelle happens with dehydration because reduced body fluids lower the volume inside the skull’s soft spots, pulling the fontanelle inward. A bulging fontanelle suggests excess fluid or pressure, which can occur with overhydration or other causes of increased intracranial pressure, making the soft spot protrude. So the statement that a sunken fontanelle indicates dehydration and a bulging fontanelle indicates overhydration is the best choice. Keep in mind that fontanelle appearance can be influenced by crying or fever, so it should be considered along with other hydration signs like mucous membranes, skin turgor, and urine output.