Blood in the stool can be bright red, maroon in color, black and tarry, or occult (not visible to the naked eye). Causes of blood in the stool range from harmless, annoying conditions of the gastrointestinal tract such as hemorrhoids and anal tears (anal fissures) from straining against hard stools with constipation to serious conditions such as cancer. Blood in the stool should be evaluated by a health care professional.
Rectal bleeding (known medically as hematochezia) refers to passage of bright red blood from the anus, often mixed with stool and/or blood clots. Most rectal bleeding comes from the colon, rectum, or anus and can be associated with diarrhea. The color of the blood during rectal bleeding often depends on the location of the bleeding in the gastrointestinal tract. Generally, the closer the bleeding site is to the anus, the blood will be a brighter red. Thus, bleeding from the anus, rectum, and the sigmoid colon tend to be bright red, whereas bleeding from the transverse colon and the right colon (transverse and right colon are several feet away from the anus) tend to be dark red or maroon colored.
In some patients, bleeding can be black and "tarry" (sticky) and foul smelling. The black, smelly, and tarry stool is called melena. Melena occurs when the blood is in the colon long enough for the bacteria in the colon to break it down into chemicals (hematin) that are black. Therefore, melena usually signifies bleeding is from the upper gastrointestinal tract (for example, bleeding from ulcers in the stomach or the duodenum or from the small intestine) because the blood usually is in the gastrointestinal tract for a longer period of time before it exits the body. Sometimes melena may occur with bleeding from the right colon. On the other hand, blood from the sigmoid colon and the rectum usually does not stay in the colon long enough for the bacteria to turn it black. Rarely, massive bleeding from the right colon, from the small intestine, or from ulcers of the stomach or duodenum can cause rapid transit of the blood through the gastrointestinal tract and result in bright red rectal bleeding. In these situations, the blood is moving through the colon so rapidly that there is not enough time for the bacteria to turn the blood black.
Sometimes, bleeding from the gastrointestinal tract can be too slow to cause either rectal bleeding or melena. In these patients, bleeding is occult (not visible to the naked eye). The blood is found only by testing the stool for blood (fecal occult blood testing) in the laboratory. Occult bleeding has many of the same causes as rectal bleeding and may result in the same symptoms as rectal bleeding. It is often associated with anemia that is due to loss of iron along with the blood (iron deficiency anemia).
Causes of rectal bleeding include hemorrhoids, anal fissure, proctitis, Crohn's disease, diverticulosis, ulcerative colitis, rectal ulcer, rectal prolapse, ischemic colitis, angiodysplasia, rectal trauma, anal cancer, colon cancer, proctitis from radiation therapy, and others.
For more information, please see the colon cancer screening and fecal occult blood test articles.
Related Symptoms & Signs
Other causes of rectal bleeding
- Esophageal Varices
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Causes of Rectal Bleeding
Amebiasis (Entamoeba Histolytica Infection)
Amebiasis is an infection caused by an amoeba. Signs and symptoms include bloody stools, abdominal pain, weight loss, fever, and gas. Treatment may involve taking luminal agents or antibiotics. Surgery may be indicated for various reasons.
Anal cancer, cancer located at the end of the large intestine, has symptoms that include anal or rectal bleeding, anal pain or pressure, anal discharge or itching, a change in bowel movements, and/or a lump in the anal region. Treatment for anal cancer may involve radiation, chemotherapy, or surgery and depends upon the stage of the cancer, its location, whether cancer is eradicated after the first treatment, and whether the patient has HIV.Anal cancer is usually curable when found localized. Early detection remains the key to long-term survival as it is in many forms of cancer.
An anal fissure is a small tear or cut in the skin lining of the anus. Pain and/or rectal bleeding during bowel movements are common symptoms of anal fissures. Treatment includes increasing liquid intake, using stool softeners, prescription medications, and surgery.
Can You Pop a Hemorrhoid?
Hemorrhoids or piles are swollen, inflamed veins around the anus or lower part of the rectum (the terminal part of the large bowel). They often get better on their own within a few days, but some may need medications and even surgery to go away. You must not pop a hemorrhoid because doing so can lead to painful and serious complications. You must always consult your doctor for a definitive diagnosis and treatment.
Can You Still Poop With Impacted Feces?
Digestion is the process of breaking down food in the gut so that it is in easily absorbable forms. The food travels from the mouth to the food pipe, stomach, small bowel, and large bowel to be finally eliminated through the anus. The small bowel (small intestine) absorbs nutrients from the food.
Colitis refers to inflammation of the inner lining of the colon. Symptoms of the inflammation of the colon lining include diarrhea, pain, and blood in the stool. There are several causes of colitis, including infection, ischemia of the colon, inflammatory bowel disease (Crohn's disease, ulcerative colitis, infectious colitis like C. difficile, or microscopic colitis). Treatment depends on the cause of the colitis.
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Colon Cancer (Colorectal Cancer) is a malignancy that arises from the inner lining of the colon. Most, if not all, of these cancers, develop from colonic polyps. Removal of these precancerous polyps can prevent colon cancer.
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Crohn's disease is a chronic inflammatory disease, primarily involving the small and large intestine, but which can affect other parts of the digestive system as well. Abdominal pain, diarrhea, vomiting, fever, and weight loss are common symptoms and signs.
Crohn's Disease vs. Ulcerative Colitis
Crohn's disease and ulcerative colitis are diseases that cause inflammation of part of or the entire digestive tract (GI). Crohn's affects the entire GI tract (from the mouth to the anus), while ulcerative colitis or ulcerative colitis only affects the large and small intestine and ilium. Researchers do not know the exact cause of either disease. About 20% of people with Crohn's disease also have a family member with the disease. Researchers believe that certain factors may play a role in causing UC. Both Crohn's disease and ulcerative colitis are a type of inflammatory bowel disease or IBD. Crohn's disease and ulcerative colitis both have similar symptoms and signs, for example, nausea, loss of appetite, fatigue, weight loss, episodic and/or persistent diarrhea, fever, abdominal pain and cramping, rectal bleeding, bloody stools, joint pain and soreness, eye redness, or pain. Symptoms unique to Crohn’s disease include anemia and skin changes. Symptoms of unique to ulcerative colitis include certain rashes, and an urgency to defecate (have a bowel movement). Doctors diagnose both diseases with similar tests and procedures. While there is no cure for either disease, doctors and other health care professionals can help you treat disease flares, and manage your Crohn's or ulcerative colitis with medication, diet, nutritional supplements, and/or surgery.
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Is Bright Red Blood in the Stool Serious?
The presence of blood in the stool needs to be evaluated by your doctor. In most cases, the bright red blood in stools is not an immediate threat to life. The most common causes are piles, anal polyps, anal fissures and colitis (inflammation of the large bowel).
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Examples of Medications for Rectal Bleeding
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