As for whether one can eat egg custard when experiencing upper gastrointestinal bleeding, it requires specific analysis of the situation. If it is during the acute phase of bleeding, such as just after vomiting blood, at that moment, one cannot eat anything and must fast. If the upper gastrointestinal bleeding has been treated and the patient has largely recovered, then they can eat egg custard, as well as other liquid or semi-liquid foods. Therefore, whether a patient with upper gastrointestinal bleeding can eat egg custard depends on the patient's condition. Once a patient experiences upper gastrointestinal bleeding, it is crucial to seek prompt medical attention at a reputable hospital's gastroenterology department to undergo thorough examinations, such as an endoscopy, to confirm the diagnosis.