What is rectal bleeding? 

There are many possible reasons for blood in your stool. Some are harmless and temporary, while others may signal a more serious condition. Anytime you find blood in your stool, it’s always best to check it out with our doctor.

Finding blood in your stool can be alarming. Often, the underlying cause can be treated or controlled. Even if the cause isn’t serious, early diagnosis is important.

What causes rectal bleeding?

Bleeding from your rectum can occur for many reasons, including:

• Constipation. Passing hard, dry stools may scrape or tear your anal lining, causing an anal fissure. You may notice small drops or streaks of bright red blood on your stool, on your toilet tissue or in the toilet bowl.
• Hemorrhoids. These swollen and inflamed veins in your anus and rectum are another source of rectal bleeding. Again, you may notice small drops or streaks of bright red blood on your stool, on your toilet tissue or in the toilet bowl.
• Diverticular bleeding. Diverticula are small, bulging pouches in the large intestine. Diverticula may cause painless, but sometimes severe bleeding.
• Infection. Some bowel infections cause diarrhea and rectal bleeding. Abdominal cramping, nausea, vomiting and fever may be present as well. These infections are usually caused by eating contaminated food.
• Colon polyps. A polyp is a small clump of cells. Although most colon polyps are harmless, some may eventually become cancerous. You may notice bright red blood on your toilet tissue after you’ve had a bowel movement.
• Peptic ulcers. Peptic ulcers are open sores that develop on the lining of the stomach, upper small intestine or esophagus. Sometimes the ulcers bleed. In addition to upper abdominal pain, you may notice dark blood in your stools or black, tarry stools.
• Inflammatory bowel disease. Ulcerative colitis and Crohn’s disease are examples of inflammatory bowel disease. These often painful and debilitating conditions cause chronic inflammation of the digestive tract. Food moving through your digestive tract can cause the inflamed tissue to bleed. You may notice bright red blood in the toilet bowl or darker blood mixed with your stool.
• Lack of blood supply to the bowel. If the blood flow to your small intestine or colon is reduced, you may develop intestinal ischemia. This may cause bright red or maroon-colored blood in your stool.
• Colorectal cancer. Most colon and rectal cancers begin as small, harmless clumps of cells called polyps. Eventually, some of these polyps may become cancerous. You may notice rectal bleeding, along with a change in bowel habits, narrow stools, abdominal discomfort, a feeling that your bowel doesn’t empty completely and unexplained weight loss.

In addition, iron supplements, certain foods — such as beets, licorice or blueberries — and some medications — such as bismuth subsalicylate (Pepto-Bismol) — may change the color of your stools to red, maroon or black.