You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is A patient comes with hematemesis and melena. On the upper GI endoscopy there was no significant finding. 2 days later the patient rebleeds. Next line of investigation is: and explain in detail?
Ans. (b) Repeat upper GI endoscopyRef: Sabiston 19th Edition, Page 1166* Endoscopy is advised even in cases in which previous endoscopy doesn't show any abnormality.