Final answer:
Gastrointestinal bleeding should be suspected if a patient presents with hematemesis.
Step-by-step explanation:
Gastrointestinal bleeding should be suspected if a patient presents with hematemesis. Hematemesis refers to the vomiting of blood, which can be a sign of bleeding in the gastrointestinal tract. It is important to note that dyspnea, hematuria, and hemoptysis are not typically associated with gastrointestinal bleeding.