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Dr. Praveen Kammar


Surgical Oncologist

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Stomach Tumor | 30 May 2022, Monday

Red Blood in Stool (Poop) – Is it a Sign of Cancer

complications of colon cancer

If you have darker-coloured stools or observe apparent blood in your stool, this could be a sign of rectum or intestinal bleeding. There may occasionally be bleeding present but not visible to the naked eye. This is called Occult (hidden) blood in stools, and it will not be identified until a stool test is done.

Blood in the stools is often an indication of rectal or bleeding from the left half of the colon ( last part of colon that joins the rectum), which could be a symptom of colon or bowel cancer. However, there are much more common causes compared to cancer.  Haemorrhoids may also result in rectal bleeding. Haemorrhoids patients typically report symptoms that fluctuate with flare-ups, whereas cancer-related rectal bleeding typically persists or increases. The presence or absence of pain does not actually indicate the underlying cause. Bleeding from haemorrhoids ( piles ) is usually painless unless it is associated with fissure or thrombosis. Most of the bleeding in rectal and colonic cancer is painless. 

If there is bleeding in the intestine before rectum and left colon, it usually results in dark red or black coloured stools (poop) and you will not notice obvious blood in stools. This is because the blood that has entered the intestine stays there for a longer period and gets degraded. The degraded products mix with stool and give a dark/black colour to the stool. Black-coloured stools usually indicate bleeding in the stomach or upper intestine while dark red blood mixed with stools indicates bleeding in the right half of the colon (first part of the large intestine).

A must read, Why Liver Cancer is so deadly

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Is blood in stool dangerous?


When you wash after a bowel activity or see bloodshed in the toilet, it can be frightening. But most of the time conditions causing this are not very serious.  Haemorrhoids or anal fissures are two prevalent causes of rectal bleeding, which is fortunate given that most of these conditions are not life-threatening. The majority of persons with light rectal bleeding don’t have colon cancer or any other serious illness. 

However, without a clinical examination, it is impossible to determine the cause of bleeding. Hence,  you should get in touch with your doctor as soon as you see any blood in your stools or bleeding out the rectum. They can advise you on if and when you must get checked out or have further testing to determine the cause.

Is Blood in Stool Cancerous or Not ?

Not all types of blood in stool are cancerous. Here are some symptoms of non-cancerous and cancerous blood stools. 

Changes in your regular bowel routine or blood in the stool are two important signs of bowel cancer. Although they might also be present with other illnesses. Hence it’s necessary to visit your doctor. 

Signs of cancerous blood in stool or large bowel cancer :

  • Blood in your faeces (poop) or bleeding out from back channel (rectum)
  • Variations in your regular bowel pattern, such as constipation, more frequent pooping, or looser poop
  • A lump in your belly or back passage, usually on the right side, that your doctor may feel
  • Even after releasing your bowels, you still feel as though you need to push in your back canal (like you’ll have to poop).
  • shedding weight
  • discomfort in your back or abdomen
  • fatigue and shortness of breath brought on by an abnormally low quantity of red blood cells (anaemia)

Cancer can obstruct the bowel occasionally. We refer to this as an intestinal blockage. The signs consist of:

  • Abdominal aches that hurt
  • Experiencing bloat
  • Constipation and difficulty breathing
  • Becoming ill
  • An intestinal blockage is a serious situation. If you suspect a bowel obstruction, consult your doctor right away or visit A&E at the closest hospital.

Non-cancerous blood in stool :

Haemorrhoids, often known as piles, are enlarged veins in the lower rectum and anus that resemble varicose veins. External haemorrhoids, which appear underneath the skin surrounding the anus, are haemorrhoids that form outside the rectum (external haemorrhoids).


  • Inflammation or itching in the anal area
  • Any discomfort or pain
  • Your anus is swollen.
  • Bleeding
  • bleeding that is painless during bowel motions. Small quantities of light red blood may be seen on your toilet paper or in the bowl.
  • a prolapsed or projecting haemorrhoid that pushes through the anal orifice, causing discomfort and irritation.

Also Read : How to Detect Stomach Cancer Early?

Black Stool with No Pain

Some meals have the ability to change the colour of your excrement. You can get a stool that is green, yellow, or even black. This can occur for a number of reasons, including consuming foods with intense colour pigments or having a condition like celiac disease or inflammatory bowel disease that produces too much biliary secretion during digestion.

Blood frequently causes your stool to seem extremely dark and nearly black. Your excrement can also appear unusually dark if you consume foods like red gelatin, black licorice, beetroot, dark berries (blackberries and blueberries), and olives. This might be mistaken for blood in the faeces with ease. Consider your recent diet if you experience really dark poop throughout a bowel movement. There’s a possibility because what you ate contributed to your typically dark stool.

stages of colorectal cancer

Is Red Stool in Women Different from Men?

Red stools can result from eating red foods like beets or from bleeding in the lower GI tract. A haemorrhoid, rectal fissure, abrasions, bowel inflammation, stomach or intestine bleeding, or colorectal cancer are only a few possible surface causes of the bleeding. The causes are nearly the same in men and women.

Also Read : What is a Colostomy?

When to worry?

Rectal bleeding may occasionally be a sign of a problem that is easily manageable. Most commonly haemorrhoids or fissures. Rectal bleeding, however, may occasionally signal a serious illness like colorectal cancer. It’s critical to monitor any bleeding you experience. Call your doctor to have it looked at if it’s heavy, frequent, or persistent and has other accompanying symptoms discussed above.




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