A black or red colored stool may be caused by something as benign as an iron supplement but it could also be an indication of bleeding somewhere in the upper or lower gastrointestinal tract. Blood is an important warning sign for both serious gastrointestinal problems such as cancer and relatively common problems like hemorrhoids.
The medical term for passing stools that are black and foul smelling due to the presence of blood is "melena." To detect how much blood is passed in a black stool a physician may order a fecal occult blood test. Melena is diagnosed if 6 tablespoons (200 milliliters) of blood or more was passed. The darkened color of the blood usually indicates that the bleeding is coming from higher up in the gastrointestinal tract and not from the colon. This type of bleeding may be caused by:
•bleeding ulcer
•gastritis
•esophageal varices
•tear in the esophagus from violent vomiting (Mallory-Weiss tear)
An ulcer is a sore on the lining of the stomach which can cause bleeding. Stomach ulcers are typically caused either by infection with a bacterium called Helicobacter pylori (H. pylori) or by use of pain medications known as NSAIDs (nonsteroidal anti-inflammatory drugs).
Gastritis is the inflammation of the stomach lining and can be caused by overindulging in alcohol or food, eating spicy foods, smoking, infection with bacteria or prolonged use of NSAIDs. Conditions which can lead to gastritis include pernicious anemia, autoimmune disorders, and chronic bile reflux.
A black stool caused by food, supplements, medication, or minerals is known as "false melena." Iron supplements, taken by many women to combat iron-deficient anemia, may cause stools to be black or even greenish in color. Multivitamins that contain iron may also have the same effect. In addition, foods that are dark blue or black in color may cause black stools. Substances that can cause false melena are:
•black licorice
•blueberries
•iron supplements
•lead
•Pepto-bismol
The passage of red or maroon colored stools is known as "hematochezia." The brighter color of the blood indicates that it may be coming from a source in the lower gastrointestinal tract. A physician should investigate blood in the stool to rule out potentially serious conditions. Causes of red or maroon stools can include:
•hemorrhoids
•anal fissures
•colon polyps or colon cancer
•diverticular bleeding
•inflammatory bowel disease
A common source of bright red blood in the stool or on toilet paper is hemorrhoids. Hemorrhoids are enlarged veins in the rectal area that may burst and bleed. Hemorrhoids are not usually serious, and can often be treated effectively with over the counter medications. Troublesome hemorrhoids that won't heal may need the attention of a physician or prescription medication.
A fissure is a tear or ulcer in the lining of the anal canal (the last part of the rectum before the anus). Fissures can occur in anyone, but are more common in middle age or young adults and can cause bright red bleeding. Acute fissures generally heal with non-invasive treatments.
Colon polyps can also cause red blood to appear in the stool. Polyps are growths on the inside of the colon that are believed to be the precursors to colon cancer. Blood from polyps or colon cancer is not always visible in the stool, even though it is present. This type of blood is called "occult blood," and can be identified with a simple test. The fecal occult blood test is important for anyone who is at risk of developing colon cancer.
Inflammatory Bowel Disease (IBD) and diverticular disease are also sources of bleeding from the gastrointestinal tract. Both Crohn's disease of the colon and ulcerative colitis can result in blood passed in the stool, frequently in the form of diarrhea. Pouches in the colon wall (known as diverticula) caused by divercular disease can often produce considerable amounts of blood in the stool.
Finally, several different types of food with natural or artificial coloring may also cause red colored stools. These can include:
•red gelatin, popsicles, or Kool-Aid
•tomato juice or soup
•large amounts beets
Blood in the stool may not always be serious, but it should always be checked by a physician. Any change in bowel habits, such as color, odor, frequency, or consistency (constipation or diarrhea) that does not clear up within a few days is reason to make an appointment with a family practitioner or a gastroenterologst.
Common Causes of Bleeding in the Digestive TractEsophagus
Stomach
Small Intestine
Large Intestine and Rectum
