Rectal bleeding can arise from anywhere in your gastrointestinal tract. Bright red blood coming from the anus, or mixed with faeces is often, but not always, a minor issue. Pink toilet water or red spots on toilet paper are often the first indication of bleeding.

Where does the blood come from?

Rectal bleeding usually comes from either the colon (large intestine), rectum, or anus.The colour of blood seen is often a good clue about where it came from. The closer the bleeding to your anus, the brighter red the blood will usually be. Dark red blood often comes from higher up.

If the bleeding source is at the top of the colon, the blood may have been there long enough to turn black, leaving the stools with a tarry appearance. However, massive bleeding from as far up as the stomach can send blood rapidly through the colon without it turning black, and can lead to bright red rectal bleeding.

What are the most common cases of rectal bleeding?

1. Anal Fissure.
   This a common and painful tear in the lining of the anal canal. Caused by passing hard stools, or chronic diarrhoea, it is frequently mistaken for haemorrhoids. After the lining is torn, any bowel movements will be painful, but little blood is evident. Haemorrhoids, on the other hand, do not generally cause pain during a bowel movement. Treatment usually comprises frequent warm baths and the use of bulking agents to keep the stools soft.
2. Haemorrhoids.
   Swollen or dilated blood vessels near your anus can cause bleeding or itching. Bleeding from haemorrhoids is usually mild, but iron deficiency anaemia can occur if bleeding is left untreated for months, or years.
3. Diverticulosis.
   Most frequently appearing over the age of 50, diverticulosis may be caused by years of high pressure spasms, or weakness in your colon wall. Diverticula are permanent sacs or pockets that poke out from the colonic wall. These can occasionally bleed, and hospitalisation or surgery is sometimes necessary to correct the condition.
4. Colon Cancers and Polyps.
   The greatest fear about bleeding from the rectum is cancer. Polyps are benign, but if they grow large enough, they can bleed. Some polyps can turn into cancer. Bleeding from either is usually mild, and its colour can range from bright red to black.
5. Proctitis and Colitis.
   Colitis is inflammation of the colon, and proctitis is inflammation of the rectum. These conditions have a variety of causes, including bacterial and viral infections, as well as some diseases, like inflammatory bowel disease.

How can the cause and location of recal bleeding be determined?

A physical examination and comprehensive medical history is first obtained. Blood tests can be helpful, and a range of diagnostic procedures may be undertaken, including colonoscopy.