Blood from the ass has nothing to do with the kidneys. Dark blood is usually more serious cuz it means it is higher up in the GI tract, such as possibly a bleeding ulcer in the stomach. When i say dark i mean like stool like tar.
Bright red blood could be hemorrhoids or fissures. If it were anal fissures it would hurt alot. Internal hemorrhoids dont hurt. External ones sometimes do hurt. If you are constipated or pushing alot it points to hemorrhoids. Go up on the bran/fiber and get some colace to soften your stools. If you lose enough blood you could become anemic and pass out like someone posted earlier. If you are dizzy i would definitley go see a doc. If not, its probably just hemorrhoids and not necessary to see a doc. If you are putting out ALOT of clots then i would go see a doc. If you are dizzy or weak or symptomatic at all, go to the ER. If you are older and/or have other medical problems, then definitely go to the ER or doc ASAP.
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