Type of Blood, Cause and Location
Bloody stool is an abnormal finding. Although on a microscopic scale our bodies discard spent and dead blood cells regularly, visible and/or testable blood in the stool reflects a problem. The presence of bright or dark "tarry" stools is very important because it can allude to the location of the bleeding and where along the gastrointestinal tract the problem is occurring. Bright red blood can be symptomatic of a problem lower in the intestinal tract and closer to the rectum. Darker stool, which indicates the blood is not "fresh," could be from a problem up closer to, and possibly including, the stomach.
Hemmorhoids as a Cause
People with hemorrhoids can experience periodic irritation of these vericose veins by such things as straining with bowel movements and hard stools. Because the walls of these hemorrhoidal veins are thin, minor tearing can occur, causing bleeding and the presence of bright red blood in the stool and in the toilet after a BM. Occasionally, the mere act of wiping after a bowel movement can cause hemorrhoids to bleed.
Tumors
More serious things such as tumors of the lower colon and rectum can cause bright red blood to be present in the stool. These situations typically manifest themselves as painless bleeding into the stool and often are the first outward sign that there is something wrong. Pressure on blood vessels and mucous linings of the rectum and colon can cause thinning of the tissues with resultant tears and bleeding.
Gastric Ulcers
If left untreated, ulcers in the stomach and/or small intestine can be significant sources of blood in the stool. Ulcers are literally "sores" of the stomach lining and can often be problematic from bleeding. Blood in the stool from these sources is dark in color because there is no remaining oxygen in the blood cells.
