I answer care plan and nursing diagnosis questions all the time. In order to come up with a nursing diagnosis you have to have a list of patient symptoms. GI bleeding can result in many symptoms. What are your patient's symptoms? Give me a list of your patient's symptoms and I will help you come up with nursing diagnoses.
For GI bleeding you would be assessing the patient's abdomen, bowel sounds, any abdominal pain, number of stools a day, color and consistency of stools, presence of any hemorrhage, presence of any bright red blood in stools, hemoglobin and hematocrit levels, presence of any nausea and vomiting and the color and hemoccult results of the vomitus, signs or symptoms of blood loss anemia (skin pallor, nailbed pallor cyanosis, weakness, vertigo, headache, drowsiness, dyspnea, tachycardia, palpitations, chest pain, fever).
There are many causes of GI bleeding. It is NOT the nurses job to figure out why a patient is bleeding. It is our job to help improve, stabilize or support the patient's condition. It is the doctor's job to treat the GI bleeding. We can help in carrying out the doctor's orders. Part of nursing education is to understand the underlying pathophysiology of GI bleeding, but if you have no specific information on what the underlying cause of this patient's bleeding is, then you must rely on the symptoms to develop the plan of care. You would do that anyway even if you knew what was causing the bleeding. Go back to the other post I did for you on the things to look for in the medical record as well as doing your physical assessment of the patient. Then repost with a list of the patient's symptoms.