The term melenic stools is sometimes used to refer to black, tarry stools or blood in stools. In addition, melenic stools may indicate a digestive symptom disorder or injury. Although black, tarry stools often indicates the presence of blood in the stool, a condition called hematochezia also refers to maroon- or red-colored stools. Generally, blood in the stool can originate from anywhere in the digestive tract, from the mouth to the anus.
Generally, melenic stools indicate that blood is originating in the upper portion of the gastrointestinal tract. This part of the gastrointestinal system includes the esophagus, beginning of the small bowel, and the stomach. When stools take on a tarry appearance, it means that they have been exposed to digestive juices. Sometimes ulcers in the stomach caused by certain medications can cause bleeding of the upper gastrointestinal tract.
Usually, bright red stools indicate that blood is originating from the lower gastrointestinal tract, which encompasses the rectum, large bowel, and anus. Certain conditions such as diverticulosis and hemorrhoids can cause frank blood in the stool. Infrequently, abnormal blood vessels and tumor formation can cause lower gastrointestinal bleeding. Sometimes, rapid or massive stomach bleeding can cause bright red stools. Certain medications such as Pepto-Bismol® and iron supplements can cause melenic stools, which is usually transient and harmless.
Sometimes, certain foods can cause melenic stools. These foods include black licorice and blueberries or blackberries. Tomatoes and beets can mimic the appearance of blood in stools and in cases like these, a physician can perform a test on the stool to rule out melena. Other causes of melenic stools are gastritis, which is an inflammation of the lining of the stomach and bowel ischemia. Typically, bowel ischemia causes the intestines to lack adequate blood flow, causing bleeding. Rarely, a foreign body or trauma to the gastrointestinal tract can produce melenic stool.
Treatment for melenic stools depends on the cause. Determining the source of blood in the stools necessitates a complete physical examination and possibly blood tests that include a complete blood count. Melena may cause anemia, which may be indicated by a decrease in red blood cells. Other diagnostic tests may include an upper and lower GI series, ultrasonography and stool specimen testing. Although blood in the stool can indicate a harmless condition, other, more ominous conditions need to be ruled out before a diagnosis can be effectively made.