A 6-month-old infant with a ventricular shunt presents with irritability, vomiting, and a bulging fontanel. The nurse suspects:

Choice A rationale While dehydration can cause irritability and poor feeding, it typically manifests with depressed fontanels, not a bulging fontanel, which is a hallmark sign of increased intracranial pressure. Dehydration would also likely present with dry mucous membranes and decreased urine output, differentiating it from shunt issues. Choice B rationale The combination of irritability, vomiting, and a bulging fontanel are classic clinical indicators of increased intracranial pressure (ICP) in an infant. This constellation of signs strongly suggests that the ventricular shunt is obstructed or malfunctioning, preventing adequate cerebrospinal fluid drainage. Choice C rationale Normal shunt function maintains cerebrospinal fluid (CSF) flow, keeping the intracranial pressure within the normal range, preventing the pathological signs of obstruction. A normally functioning shunt would result in the resolution of or prevention of symptoms like a bulging fontanel, irritability, and vomiting. Choice D rationale Gastroenteritis, or infectious diarrhea, primarily presents with diarrhea, vomiting, and often fever. Although vomiting and irritability can occur, a bulging fontanel is highly specific to elevated intracranial pressure and is not a symptom typically associated with routine infectious gastroenteritis.