When should EMS be summoned according to the guidelines?

The correct choice indicates that EMS should be summoned in cases of severe bleeding or persistent abdominal pain because these situations often pose immediate health risks that require professional medical assessment and intervention. Severe bleeding can lead to significant blood loss, shock, or even death if not addressed swiftly. Similarly, persistent abdominal pain might be a symptom of a serious condition, such as appendicitis or internal injuries, which can worsen without timely medical care.

The guidelines emphasize the importance of recognizing medical emergencies where timely intervention is crucial. While the other options represent scenarios that may require attention, they do not indicate the same level of urgency or medical threat associated with severe bleeding or ongoing abdominal pain. In those instances, the summoning of emergency medical services is vital to ensure the affected individual receives the necessary care as quickly as possible.