Rectal Bleeding and Colo-Rectal Cancer


Cololorectal cancer- cancer that starts in the large intestine (colon) or the rectum (end of the colon) is a major public health problem; Mortality is highest in those diagnosed with later stage disease, earlier diagnosis is very important to improve survival.

Rectal bleeding and a change in bowel habit are the most important symptoms of colorectal cancer. Every rectal bleeding is not piles and Patient with piles (hemorrhoids) and bright red bleeding may still have colorectal cancer. Thus every rectal bleeding should be cautiously examined by a doctor or a colorectal specialist to rule out the possibility of colorectal cancer.

Rectal Bleeding:

The occurrence of blood loss per rectum or blood in the stool is common and very freighting. While most of the time it is not because of a serious cause, common causes are hemorrhoids and anal fissure, it may be the first symptom of a colorectal cancer.

The color of blood during rectal bleeding often depends on the location of the bleeding in the gastrointestinal tract. Generally, the closer the bleeding site is to the anus, the brighter red the blood will be. Thus, bleeding from the anus, rectum, and the sigmoid colon tends to be bright red, whereas bleeding from the transverse colon and the right colon tends to be dark red or maroon-colored

Common Causes of rectal bleeding:

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

anal fissures,
cancers and polyps of the rectum and colon,
ulcerative colitis,
infectious colitis,
ischemic colitis,

Anal Fissure:

A anal fissure is a painful condition in which the lining of the anal canal is torn. An anal fissure is caused by constipation or a forceful bowel movement. Bleeding with an anal fissure is small and usually is noticed in the toilet bowl or on the toilet paper as bright red in color and is associated with pain or burning sensation after or while passing stool .


Hemorrhoids are dilated and swollen cushions (pads of tissue) in the anal canal, they may project into the anal canal to form visible swellings. Bright red blood coats the stool or blood may drip into the toilet or stain toilet paper. Bleeding from hemorrhoids is usually mild.

Colon cancers and polyps:

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 iron deficiency anemia.

Relevance to Colorectal Cancer: Diagnosing Cause of Rectal Bleeding

An accurate diagnosis of the location and the cause of rectal bleeding is important for proper treatment. Diagnosis is usually based on the history and rectal examination, anoscopy, flexible sigmoidoscopy, colonoscopy, radionuclide scans, angiograms, and blood tests.

The age of the patient is an important clue to the cause of rectal bleeding. A recent change in bowel habit such as constipation or diarrhea suggests the possibility of cancer of the colon

Contributory elements for colorectal cancer include high fat, low-fiber, red meat-filled diets and smoking cigarettes Symptoms of Colon cancer are usually pain in the lower stomach, blood in the stools, irregular bowel movements, anemia and sudden weight loss.

High Risk Factors and Symptoms for colon and rectal cancer

Age 50 or older
Eat a diet high in red or processed meats
Blood in stool
Recent change in bowel habit such as constipation or diarrhoea
Unexplained weight loss
First degree relative with colorectal cancer or colon ployp
Patients with Chronic inflammatory bowel disease such as ulcerative colitis or Crohn’s disease
Unexplained anemia / weight lodss

Screening Methods

Whether or not hemorrhoids and anal fissures are found, if there has been rectal bleeding, the colon above the rectum needs to be examined to exclude colorectal cancer by either flexible sigmoidoscopy or colonoscopy, procedures that allow the doctor to examine approximately one-third or the entire colon, respectively.

Colonoscopy is the most widely used procedure for evaluating rectal bleeding as well as occult bleeding. It can be used to detect polyps, cancers, diverticulosis, ulcerative colitis, ulcerative proctitis, Crohn’s colitis, ischemic colitis, and angiodysplasias throughout the entire colon and rectum

Fecal occult blood testing (FOBT) is the only screening modality that has been shown to be effective thus it should be routine test for individuals age 50 and above. But it detects only those cancers or polyps which are bleeding.

Flexible sigmoidoscopy allows examination of lining of the lower one third of the colon and rectum (Portion of the intestine where most polyps and cancers occur). If combined with testing the stool for hidden blood, many cancers and polyps can be detected.

Colonoscopy is gold standard for complete large bowel evaluation. When a polyp or cancer is detected by flexible sigmoidoscopy, or if a person is at high risk to develop colon and rectal cancer, colonoscopy provides a safe, effective means of examining the full lining of colon and rectum. Colonoscopy is used to diagnose colon and rectal problems and to perform biopsies and remove colon polyps. Most colonoscopies are done on an outpatient basis.

Other screening tests i.e. barium enema, and CT colography (virtual colonoscopy) may not be as effective and reliable as occult blood testing or colonoscopy

Some people assume that their rectal bleeding is due to ‘piles’ and do not get it checked. While Haemorrhoids are perhaps the most common cause of rectal bleeding, however, every rectal bleeding is not piles and patients presenting with bright red bleeding and haemorrhoids may still have cancer.

To conclude :

Rectal bleeding should be assessed by a doctor to rule out other serious causes of bleeding specially cancer.

Persistent rectal bleeding or a change in bowel habits or high risk category patients can be sufficient reason to evaluate the patients for colorectal cancer

If colorectal cancer is detected early thru a colonoscopy procedure, this threatening cancer is 93% treatable.

Polyps are precancourous condition and generally present in the colon for years before they become cancerous. Polyps can be removed very safely from the colon, preventing progression to cancer.

Changing your diet and lifestyle is important. Some evidence suggests that low-fat and high-fiber diets may reduce your risk of colon cancer.

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