Bowel bleeding is a popular term for rectal bleeding, what refers to blood in the bowel movement.
These terms only mean that blood comes out from the bowel/rectum, but actual origin of the blood may be in the bowel (small/large intestine, rectum), stomach, esophagus, throat, mouth, nose, para-nasal sinuses, lungs (after swallowing blood) or any other organ from which the blood may flow into the bowel (for example in stitching injuries or metastatic cancer).
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