What Causes Blood in the Stool?

If blood is present in the stool, the first step is to observe the color and quantity of the blood, as well as the pattern of bleeding. For instance, if the blood is bright red, appears on the surface of the stool, and is present only in small amounts—sometimes even visible as streaks on toilet paper after wiping—this is most commonly indicative of hemorrhoidal bleeding. In such cases, consultation with a colorectal surgeon for hemorrhoid management is usually sufficient.

In contrast, if the volume of blood is substantial, and the blood appears either bright red or dark red and is thoroughly mixed with the stool, further evaluation is warranted.

Additionally, increased mucus in the stool may be observed. This warrants careful attention, as it may suggest lower gastrointestinal (GI) bleeding. Potential causes include inflammatory bowel disease (e.g., ulcerative colitis, an autoimmune condition), infectious enterocolitis (e.g., amoebic dysentery), or colorectal malignancies such as rectal or colon cancer. All of these conditions can manifest with hematochezia (visible blood in the stool). If the cause remains unclear, prompt medical evaluation at a hospital is essential.

A third scenario involves post-defecation arterial spurting—i.e., sudden, forceful bleeding immediately after bowel movement. This type of bleeding is often attributable to vascular abnormalities, most commonly hemorrhoids. Although alarming in appearance, this condition is typically not life-threatening; timely consultation with a colorectal surgeon is recommended for appropriate management.