As a rule of thumb, the farther the blood has to travel, the darker it'll be. Blood from high up enough in your GI tract will be a black, tarry substance, NOT red, but it's absolutely blood and you need to get that checked out ASAP.
Edit: To be clear “severely dehydrated” is kinda an important factor here. Point being that if the cause is obvious I dont see why you’d get a colonoscopy. Please correct me if im wrong instead of just downvoting for anyone who knows more about this thx ^^
But yeah, if it happens once it’s not necessarily a problem. It’s when you keep having bloody stool that it’s a good idea to get checked.
Wrll, actually, if thebimjury is beyond "a self applied band aid can fix it", see a doctor as well!
> fecal occult blood test
Often used to screen patients for colonoscopies. Screening is looking for disease in the asymptomatic: "occult" means it's not visible to the naked eye, you're looking for blood even though the patient has not noticed any. The symptomatic don't need screening, they need diagnosis and thus proceed directly to colonoscopy. Or endoscopy if upper gastrointestinal tract bleeding is suspected.
Also there’s supposedly a poop test called fecal occult blood test that has a high rate of detecting colorectal cancer that you do over the course of 3 years. I saw this on nhk Doctor's Insight: https://www3.nhk.or.jp/nhkworld/en/ondemand/video/2086035/