Final answer:
To assess for signs of increased intracranial pressure in an infant with hydrocephalus, the nurse should monitor the anterior fontanel for signs of bulging or increased tension.
Step-by-step explanation:
When an infant with hydrocephalus experiences a diminishing level of consciousness, a priority intervention is to assess for signs of increased intracranial pressure. The nurse should monitor the infant's anterior fontanel for signs of bulging or increased tension, as this can indicate elevated pressure within the skull. Palpating the anterior fontanel can help identify any changes in its size or firmness.