What causes bleeding in the digestive tract?

Stomach acid can cause inflammation that may lead to bleeding at the lower end of the esophagus. This condition, usually associated with the symptom of heartburn, is called esophagitis or inflammation of the esophagus. Sometimes a muscle between the esophagus and stomach fails to close properly and allows the return of food and stomach juices into the esophagus, which can lead to esophagitis. In another, unrelated condition, enlarged veins (varices) at the lower end of the esophagus may rupture and bleed massively. Cirrhosis of the liver is the most common cause of esophageal varices. Esophageal bleeding can be caused by a tear in the lining of the esophagus (Mallory-Weiss syndrome). Mallory-Weiss syndrome usually results from vomiting but may also be caused by increased pressure in the abdomen from coughing, hiatal hernia, or childbirth. Esophageal cancer can cause bleeding.

The stomach is a frequent site of bleeding. Infections with Helicobacter pylori (H. pylori), alcohol, aspirin, aspirin-containing medicines, and various other medicines (NSAIDs, particularly those used for arthritis) can cause stomach ulcers or inflammation (gastritis). The stomach is often the site of ulcer disease. Acute or chronic ulcers may enlarge and erode through a blood vessel, causing bleeding. Also, patients suffering from burns, shock, head injuries, cancer, or those who have undergone extensive surgery may develop stress ulcers. Bleeding can also occur from benign tumors or cancer of the stomach, although these disorders usually do not cause massive bleeding.

A common source of bleeding from the upper digestive tract is ulcers in the duodenum (the upper small intestine). Duodenal ulcers are most commonly caused by infection with H. pylori bacteria or drugs such as aspirin or NSAIDs.

In the lower digestive tract, the large intestine and rectum are frequent sites of bleeding. Hemorrhoids are the most common cause of visible blood in the digestive tract, especially blood that appears bright red. Hemorrhoids are enlarged veins in the anal area that can rupture and produce bright red blood, which can show up in the toilet or on toilet paper. If red blood is seen, however, it is essential to exclude other causes of bleeding since the anal area may also be the site of cuts (fissures), inflammation, or cancer.

Benign growths or polyps of the colon are very common and are thought to be forerunners of cancer. These growths can cause either bright red blood or occult bleeding. Colorectal cancer is the third most frequent of all cancers in the United States and often causes occult bleeding at some time, but not necessarily visible bleeding.

Inflammation from various causes can produce extensive bleeding from the colon. Different intestinal infections can cause inflammation and bloody diarrhea. Ulcerative colitis can produce inflammation and extensive surface bleeding from tiny ulcerations. Crohn's disease of the large intestine can also produce bleeding.

Diverticular disease caused by diverticula—pouches in the colon wall—can result in massive bleeding. Finally, as one gets older, abnormalities may develop in the blood vessels of the large intestine, which may result in recurrent bleeding.

Patients taking blood thinning medications (warfarin) may have bleeding from the GI tract, especially if they take drugs like aspirin.

What are the common causes of bleeding in the digestive tract?

Esophagus

• inflammation (esophagitis)
• enlarged veins (varices)
• tear (Mallory-Weiss syndrome)
• cancer
• liver disease

Stomach

• ulcers
• inflammation (gastritis)
• cancer

Small intestine

• duodenal ulcer
• inflammation (irritable bowel disease)
• cancer

Large intestine and rectum

• hemorrhoids
• infections
• inflammation (ulcerative colitis)
• colorectal polyps
• colorectal cancer
• diverticular disease

source: http://digestive.niddk.nih.gov/ddiseases/pubs/bleeding/index.htm