A caregiver reports their 18-month-old child is not using their left arm after playing. What should be the nurse's immediate action?

The immediate action of conducting a full neurological assessment is critical in this scenario because sudden inability to use an arm in a young child can indicate a serious underlying condition, such as a neurological injury or significant nerve damage. Given the child's age and the report of loss of function, it is essential to assess for any signs of neurological deficits that could point to conditions like a brachial plexus injury or a stroke.

A comprehensive neurological assessment encompasses evaluating the child's motor function, sensitivity in the affected limb, and signs of immediate distress. This assessment guides further interventions and determines if immediate medical or surgical interventions are necessary.

Other options, such as checking for signs of fracture, applying a sling, or referring to physical therapy, are relevant but secondary to the urgent need to rule out any serious neurological issues. If a fracture were to be present, it may also lead to neurological compromise, making the initial assessment crucial in determining the appropriate next steps. Thus, focusing on a full neurological assessment provides the best framework for addressing the potential seriousness of the situation right away.