The blood color or in which manner the blood is found in the stool gives us the substantial evidence about the cause of the bleeding.
If the stool seems to black or tar stools, we know this blood was exposed to stomach acid and turned black due to the fermentation process. The most common reason for black stools or tar stool or in scientific term melena is stomach ulcers. These can bleed profoundly. In cases of severe bleeding the blood passes by the stomach very fast and the blood remains red and appears red in the pot.
In most cases when you find red blood in the stool, the bleeding is from the colon or large bowel. We often straight away assume it as cancer, but blood in the stool can have many other reasons such as polyps, which are benign mushroom-like growths inside the colon, or diverticel, which are small hernia in the bowel.
Bleeding can also come from an infectious process where the colon inlining is irritated and can bleed which in most cases is associated with diarrhea. In most of the cases the stool and blood are mixed or blood comes at the same time as stool into the toilet commode.
Many patients say that they have a a small quantity of red blood on top of the stool or they see it when they clean themselves and notice blood on the toilet paper. The most common reason of this sort of bleeding is hemorrhoids found in the anal and inner part of the rectum. Patients often report more bleeding when they are constipated and they have to strived hard or have had diarrhea and had to go often and rubbed too much.
When you notice blood in the stool or toilet commode try to describe it as well as you can, such as how much blood on top of stool, presence of black stools, or only on toilet paper, every time with fecal matter or only occasionally. Of course persistent blood in the rectum needs to be evaluated by a physician with a rectal examination and may be by a colonoscopy.