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Blood in the Stool (Rectal Bleeding) (cont.)

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What diseases and conditions can cause blood in the stool (rectal bleeding)?

Many diseases and conditions can cause rectal bleeding. Common causes include:

As discussed previously, it also is possible for "rectal bleeding" to be coming from the stomach and duodenum, primarily from ulcers, cancers, and angiodysplasias.

Anal fissures

An anal fissure is a fairly common, painful condition in which the lining of the anal canal is torn. An anal fissure usually is caused by physical trauma due to constipation or a forceful bowel movement through a tight anal muscle or physical trauma also may be contributing factors. Once the skin is torn, each subsequent bowel movement can be painful, and the pain often is severe. The amount of bleeding that occurs with an anal fissure is small and usually is noticed in the toilet bowl or on the toilet paper as bright red in color. The symptoms of an anal fissure are commonly mistaken for hemorrhoids, but hemorrhoids generally do not cause pain with bowel movements.

Hemorrhoids

Hemorrhoids are masses or clumps ("cushions") of tissue within the anal canal that contain blood vessels. Although most people think hemorrhoids are abnormal, they are present in everyone. It is only when the hemorrhoidal cushions enlarge that hemorrhoids become susceptible to trauma from passing stool and cause problems (such as bleeding or anal discomfort) and are considered abnormal or a disease. Like anal fissures, bleeding from hemorrhoids usually is mild and does not cause anemia or low blood pressure. Rarely, a person may develop iron deficiency anemia as a result of repeated hemorrhoidal bleeding over several months to years, especially if the dietary intake of iron is low.

Picture of the formation of hemorrhoids
Picture of the formation of hemorrhoids

Colon cancer and polyps

Tumors of the colon and rectum are growths (masses) arising from the wall of the large intestine. Benign tumors of the large intestine usually are called polyps because of their shape. Malignant tumors of the large intestine are cancers, and most are believed to have developed from polyps. Bleeding from colon polyps and cancers tends to be mild (the amount of blood loss is small), intermittent, and usually does not cause low blood pressure or shock.

Cancers and polyps of the colon and rectum can cause bright red rectal bleeding, maroon colored stools, and sometimes melena. The colon cancers and polyps located near the rectum and the sigmoid colon are more likely to cause mild intermittent bright red rectal bleeding, while colon cancers located in the right colon are more likely to cause occult bleeding that over time can lead to moderate or severe iron deficiency anemia.

Picture of the colon with colon cancer and colon polyps
Picture of the colon with colon cancer and colon polyps
Medically Reviewed by a Doctor on 8/2/2017

Source: MedicineNet.com
https://www.medicinenet.com/blood_in_the_stool_rectal_bleeding/article.htm

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