Reasons for Blood in a Stool Sample

Written by karen hellesvig-gaskell
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When blood is detected in a stool sample it can be indicative of a wide variety of conditions and diseases that can range from relatively minor to life threatening. Depending on the amount of blood that's in the stools it may not be visible to the naked eye. The quantity of blood may be so microscopic that it can only be spotted by a fecal blood test.

Anal Fissure

An anal fissure is a tiny rip in the lining of the anal passage. This type of tear may result from passing large or stiff stools during bowel movements. In addition to rectal bleeding, an anal fissure may also cause pain, burning and itching. The vast majority of anal fissures heal naturally without surgery.


Haemorrhoids are sore, irritated and swollen veins in the lower part of the rectum or anus. They are due to increased stress on the anal veins. They commonly occur from pressure during bowel movements. Women who are pregnant or have just given birth are susceptible to haemorrhoids.

When the pain and discomfort associated from haemorrhoids is mild, over-the-counter creams, ointments, suppositories or pads generally suffice. More severe cases may require surgery.

Colon Polyps

A colon polyp is a small, usually benign cluster of cells that develops on the lining of the colon. Colon polyps that are detected early can be removed safely. If they are not taken out, it's possible for them to become cancerous. While rectal bleeding is possible, polyps often don't have any symptoms.

There are several tests including a standard colonoscopy (when your doctor looks at the entire colon and rectum) that are used to screen for polyps. They also include a noninvasive fecal occult blood test that looks for blood in a stool sample.

Stool DNA testing is a new colon cancer screening method that can also can detect precancerous polyps.

Colon Cancer

Colon cancer is cancer of the large intestine that sits in the lower half of your digestive system. Blood in the stools is just one of many possible signs of this disease. Colon cancer symptoms may also include constipation, diarrhoea, narrow stools and abdominal pain. Treatment for colon cancer may include surgery, radiation and chemotherapy.

Crohn's Disease & Ulcerative Colitis

Crohn's disease is an inflammatory bowel disease (IBD) that attacks the digestive track. In addition to possible blood in the stools, the inflammation can cause abdominal pain, severe diarrhoea and weight loss.

Ulcerative colitis is another bowel disease that causes chronic inflammation of the digestive tract. Two subclasses of the disorder, left-sided colitis (left side of the colon only) and pancolitis (entire colon) have symptoms that can include blood in the stools.

Although there is no cure for these IBD disorders, proper treatment can greatly minimise their symptoms.

Anti-inflammatory drugs are often the first treatment of choice. Corticosteroids may also be considered but tend to have more side effects.

Intestinal Ischemia

A weakened blood flow to your small intestine or colon can result in a painful condition called intestinal ischemia (is-KE-me-uh). Intestinal ischemia is a potentially serious disorder but it is highly treatable. In addition to blood in the stools, there may also be an urgent need move your bowels, tenderness in the abdominal region, fever and nausea or vomiting.

Treatment options vary for intestinal ischemia but they generally involve the restoration of an adequate blood supply to the digestive tract.

Peptic Ulcers

In rare cases, peptic ulcers can cause blood in the stools. Peptic ulcers are open sores that can form on the inside lining of the stomach, in the upper small intestine or in the oesophagus. Abdominal pain is the most typical symptom of a peptic ulcer. Others may include nausea or vomiting and weight loss.

Your doctor may prescribe antibiotic medications and recommend antacids.

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