Blood in stool

Blood in stool appears due to bleeding from the lower intestinal tract, i.e., anus, rectum and colon. You can have a rough idea of the site of bleeding by the look of blood on the stools. A small amount of bright red blood on the surface of the stool or the toilet paper signifies a cause at or near the anus. Bright red Blood in stool, unmixed with stools, in larger amounts can also come from this region. Bleeding from higher up in the body is usually more intimately mixed up with the stools and is likely to be darker or maroon coloured. Small chronic bleeding, not visible to the naked eye, can only be known by testing for occult blood chemically and by microscopic examination.

Your doctor will be able to diagnose anorectal conditions that lead to blood in stool, by direct examination with a proctoscope and by digital examination. For the diagnosis of bleeding coming from higher up in the body, investigations like sigmoidoscopy, flexible colonoscopy and double contrast barium enema x-rays may be necessary.

Common Causes of Blood in stool

Haemorrhoids (piles)

Piles are masses of dilated veins in the anorectal region, usually at three equidistant points around the circumference of the anus. They are a common cause for blood in stool. They are seldom painful, unless strangulated. First-degree piles are internal and bleed at the end of defaecation, particularly if the stools are hard. Second-degree piles are external and protrude beyond the anus as uncomfortable swellings but return spontaneously. Third-degree piles remain protruding and have to be pushed in; they are liable to strangulation and need to be removed surgically.

Treatment depends upon the severity of symptoms and the amount of blood in stool. In many cases, the only therapy required is improvement in anal hygiene and administration of stool softeners, to prevent straining and friction while passing stools.

Removal of piles, when necessary, is done by surgery, cryotherapy or ligation by rubber bands applied to the base of the piles.

Anal Fistule

This is an abnormal communication between the anal canal and the skin near the anus. It is formed after an abscess near the anus has burst. The track is chronically inflamed with exudation of pus and sometimes blood in stool. The treatment is surgical.

Anal Fissure

This is a linear crack-like ulcer on the margin of the anus, which is very painful and may bleed during the passing of stools with appearance of frank blood in stool. The treatment is surgical.

Cancer of the Colon and Rectum

It is a disease that strikes the elderly. Fortunately it is uncommon in India due to high intake of fibre-containing vegetarian food, which protects us against cancer of the colon and rectum.

Rectal carcinoma may give a feeling of incomplete emptying of the rectum. It can bleed profusely. A doctor may be able to feel the mass on digital examination of the rectum.

Cancer of the colon may cause blood in stool or cause obstruction to the passage of faecal matter in the gut, resulting in increasing constipation and change of bowel habit, distension and colicky pains in the abdomen. Flexible signoidoscopy and colonoscopy, and double contrast barium enema x-rays are usually necessary for diagnosis.

All the above four conditions are surgical. It is therefore prudent to consult a surgeon when suggestive symptoms are present, so that an operative procedure can be carried out at the opportune time.


Infection are another common reason for the blood in stool.

Bacillary dysentery: This is a common cause of acute bloody diarrhoea with fever. Stool examination shows pus and red blood cells. It responds to suitable antibiotic treatment.

Amoebic dysentery: This causes chronic diarrhoea with mucus, indigestion and loss of weight. Blood in stool is only occasional and is due to secondary infection. Stool examination may show amoebae and cysts. It responds to suitable anti-amoebic treatment along with antibiotics, when necessary.

Typhoid fever: This fever is common in India. Ulcers form in the intestines, which can cause severe bleeding, usually in the third week of the fever. It is a serious complication, but is now rare. With suitable antibiotic treatment and proper rest in bed, it can be prevented.

Ulcerative colitis: It is not a common disease in India. This is frankly bloody diarrhoea, the severity of which varies from time to time with amount of blood in stool varying. Mucosa of the colon and rectum is inflamed and ulcerated. Sigmoidoscopy and barium enema x-rays are necessary for diagnosis. The disease is liable to relapses but may remain quiescent for long periods. Medical treatment with saizopyrin and corticosteroid enemas keep the disease under control.

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