### Human:\nmy stool is jet black i've had this before how long does it take for the stomach to digest and pass blood from an ulcer. i've got a lengthy history of bleeding gi's which has resulted in multiple hospitalizations for a week or more at a time each time requiring transfusions from anywhere to 9+ and sometimes up to 14 units of blood. even though i just noticed it i'm already growing weak and getting out of breath for no apparent reason something that never happened this soon before. so i was wondering if i've been bleeding in my stomach for a long time and it's just now being expelled.\n\n### Assistant: you need to get to the er now. with your medical history it is not that important when you started bleeding but rather how much you are bleeding right now. a rapid bleed in the stomach could cause black stools relatively fast. because you are weak and out of breath it would not be wise to delay an immediate medical evaluation.