Depending on a person's age and medical history, there can be a variety of causes for small intestine bleeding. This condition often is referred to as gastrointestinal (GI) bleeding. The most common causes of small intestine bleeding are ulcers, Crohn's disease, tumors or polyps and arteriovenous malformations.
Only about 5 percent of all GI bleeding occurs in the small intestine. When it does happen, it usually is the result of some abnormality within the lining of the small bowel. Blood loss can be either rapid, as the result of a hemorrhage, or slow, as would be the result of a tiny blood vessel that might have burst. Often, the first symptom aside from blood in the stool is anemia.
Ulcers normally form in the upper gastrointestinal tract. When these ulcerative lesions form in the small intestine, they usually are a side effect from using nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen or naproxen. Many over-the-counter, fever-reducing pain relievers and anti-inflammatory compounds fall into this category, as do several prescription arthritis medications.
Crohn’s disease might also result in small intestine bleeding. Crohn’s disease is an auto-immune disease for which there is no cure, only treatment for the symptoms and related conditions that often accompany this debilitating illness. It is thought to be genetic, and it usually presents while the sufferer is in his or her late teens or early 20s. Symptoms include but are not limited to diarrhea, vomiting, abdominal pain and weight loss. Although Crohn’s can affect any part of the gastrointestinal tract from the mouth to the anus, it is the most distal portion of the small bowel, the terminal ileum, that accounts for at least 50 percent of all diagnosed cases of Crohn’s.
Tumors or polyps, whether benign or malignant, also can cause small intestine bleeding. Although rarely found in the small intestine, tumors can become ulcerative and bleed. They can be single or multiple, but in most cases, these are found only during testing for other digestive problems. They might be dormant for years before discovery, with only occasional instances of stomach pain, bleeding, nausea, constipation or loose stools.
Most frequently, the cause of GI bleeding is caused by angioectasias, or arteriovenous malformations (AVMs). Fully 30 percent to 40 percent of instances of small intestine bleeding occur when these abnormal blood vessels, which are located inside the lining of the small intestine, rupture. AVMs become more likely and are very common as people grow older, and they are the single most common cause of bleeding in the small intestine in people older than 50. AVMs also frequently accompany conditions such as heart disease and kidney disease.