Colorectal Surgery

Blood in Stool: What It Could Mean

  • 											Array
        [name] => Dr Ho Kok Sun
        [avatar] =>
        [tiny_avatar] =>
        [address] => Ho Kok Sun Colorectal Pte Ltd
    3 Mount Elizabeth
    #12-09 Mount Elizabeth Medical Centre
    Singapore 228510
    Tel: 6737 2778
        [id] => 2108
        [doctor_link] =>
        [specialization] => Colorectal Surgeon
        [specialization_id] => 29
        [specialization_link] =>
  • March 14, 2022
  • 2 minutes read

Finding blood in your stool may be alarming and frightening, but there are many explanations for this, most of which are not life-threatening. Some causes are minor and benign, while others are more serious and require urgent medical attention.

Rectal bleeding refers to blood originating from the rectum or anus. It can present as bright red blood, or black to tarry stool, depending on the site of bleeding. You may notice blood in the toilet or tissue paper after a bowel movement. Rectal bleeding is not a condition in itself, but a symptom of bleeding or disease in the gastrointestinal tract. Some bleedings are also hidden or occult, meaning they are not visible to the naked eye.

Here are some common causes of rectal bleeding:


Haemorrhoids refer to swollen blood vessels in the rectum or anus that are caused by excessive pressure, usually resulting from chronic straining during bowel movements, lifting heavy objects, pregnancy and obesity. Haemorrhoids are not dangerous, but they can be painful and inconvenient in their advanced stages. They are the most common cause of rectal bleeding.

Anal fissure

An anal fissure is a tear in the lining of the anus. It is often caused by passing very hard stools, chronic constipation or diarrhea, childbirth and anal sex. Like haemorrhoids, anal fissures are not serious, but they can be very painful. Many fissures heal on their own within a few weeks; if not, further treatment will be needed.

Anal fistula

An anal fistula is a small tunnel that runs from a gland inside the anus to a hole or opening on the skin surrounding the anus. It is mostly caused by an infection in the anal gland, which causes it to become pus-filled (abscess). An anal fistula causes pain and swelling in the anal region, and may be accompanied with an odorous discharge and fever. Surgery is the main treatment.

Diverticular disease

Diverticulosis and diverticulitis are conditions that cause small pouches or bulges called diverticuli to form in the weakened areas of the wall of the large intestine. Chronic constipation and not having enough fiber in the diet are said to contribute to these illnesses. Diverticulosis refers to the presence of diverticuli; when these pouches become infected or inflamed, the condition is known as diverticulitis.

Inflammatory bowel disease

Inflammatory bowel disease is an umbrella term used to describe conditions that cause chronic inflammation in the gastrointestinal tract such as ulcerative colitis and Crohn’s disease. Both conditions are characterized by rectal bleeding and abdominal pain. If left untreated, inflammatory bowel disease can have serious complications.


Having too much digestive fluids can destroy the lining of the stomach or the intestine, causing bleeding and dark stools. Ulcers are also accompanied by symptoms like gas, bloating, nausea and vomiting, and weight loss. The most common cause of ulcers is Helicobacter pylori (H. pylori) bacteria, which can be treated via antibiotics.


Polyps are benign growths that can form on the intestine. Larger ones can bleed and cause rectal bleeding. Though most polyps are benign and harmless, they should be checked and treated promptly as some can turn into cancer.

Colorectal cancer

Colorectal cancer is among the top cancers affecting Singaporeans today. It occurs when mutations in the DNA of the cells in the colon or rectum cause cells to multiply quickly and abnormally, forming tumors. Left untreated, cancer can spread to nearby tissues and organs. As with all cancer, the key to effective treatment is through prompt diagnosis via routine screening.

Rectal bleeding can be caused by several conditions, ranging from minor to complex. Regardless, any prolonged case of rectal bleeding – especially when accompanied by other symptoms – should be checked by a doctor immediately.

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