Rectal bleeding causes

Because there are several possible causes for minor rectal bleeding, a complete evaluation and early diagnosis by your doctor is very important. Rectal bleeding, whether it is minor or not, can be a symptom of colon cancer, a type of cancer that can be cured if detected early.
There are many possible causes. Brief overview of the more common causes:

• Hemorrhoids (piles)
• Anal fissure
• Diverticula
• Crohn's disease
• Ulcerative colitis and other forms of colitis
• Polyps
• Cancer
• Angiodysplasia
• Abnormalities of the gut
• Stomach and duodenal ulcers
• Some gut infections

Another causes of rectal bleeding

Abnormalities of the gut
Various abnormalities of the gut, or the gut wall may cause rectal bleeding in young children. For example: volvulus, intussusception, Meckel's diverticulum, abnormal blood vessel development.

Stomach and duodenal ulcers
An ulcer in the stomach or duodenum may bleed. This can cause melaena - where your faeces turn black as described earlier..

Some gut infections
May cause 'bloody diarrhoea' due to inflammation of the gut caused by some infections.

There are various other rarer causes.

Angiodysplasia

Angiodysplasia is increasingly recognised as a cause of acute or chronic gastrointestinal bleeding in the elderly. Colonic angiodysplasia is a degenerative vascular lesion of the colon associated with ageing ; it should not be confused with congenital or neoplastic vascular lesions of the gastrointestinal tract. It is a well-defined clinical and pathological entity with a clear predilection for the right colon.
Diagnosis of angiodysplasia has been facilitated by the use of angiographic techniques and colonoscopy.
Although the treatment of choice is right hemicolectomy, endoscopic treatment by laser or electrocoagulation is more and more performed.
Angiodysplasia is a condition where you develop a number of enlarged blood vessels within the inner lining of the colon.
The cause is unknown, but they occur most commonly in older people. Bleeding from an angiodysplasia is painless. The blood seen can range from bright red brisk bleeding, to dark blood mixed with faeces, to melaena. An angiodysplasia may also cause occult blood loss (see below).

Cancer of the colon

Cancer of the colon and rectum are common cancers in older people. They sometimes affect younger people. Rectal bleeding is one symptom that may occur. Bleeding is often 'occult' (see later) and other symptoms are often present before visible bleeding occurs. For example, pains, anaemia, weight loss, diarrhoea or constipation. See separate leaflet called 'Cancer of the Bowel' for details. Cancers of other parts of the gut higher up from the colon sometimes cause rectal bleeding, but these are uncommon.

Polyps

A bowel polyp (adenoma) is a small growth that sometimes forms on the inside lining of the colon or rectum. Most develop in older people. About 1 in 4 people over the age of 50 develop at least one bowel polyp. Polyps are benign (non-cancerous) and usually cause no problems. However, sometimes a polyp bleeds and sometimes a polyp can turn cancerous.

Ulcerative colitis

Ulcerative colitis is a disease that causes inflammation and sores, called ulcers, in the lining of the rectum and colon. Ulcers form where inflammation has killed the cells that usually line the colon, then bleed and produce pus. Inflammation in the colon also causes the colon to empty frequently, causing diarrhea.

When the inflammation occurs in the rectum and lower part of the colon it is called ulcerative proctitis. If the entire colon is affected it is called pancolitis. If only the left side of the colon is affected it is called limited or distal colitis.

Ulcerative colitis is an inflammatory bowel disease (IBD), the general name for diseases that cause inflammation in the small intestine and colon. It can be difficult to diagnose because its symptoms are similar to other intestinal disorders and to another type of IBD called Crohn’s disease. Crohn’s disease differs because it causes inflammation deeper within the intestinal wall and can occur in other parts of the digestive system including the small intestine, mouth, esophagus, and stomach.

Ulcerative colitis can occur in people of any age, but it usually starts between the ages of 15 and 30, and less frequently between 50 and 70 years of age. It affects men and women equally and appears to run in families, with reports of up to 20 percent of people with ulcerative colitis having a family member or relative with ulcerative colitis or Crohn’s disease. A higher incidence of ulcerative colitis is seen in Caucasians and people of Jewish descent.

What are the symptoms of ulcerative colitis?

The most common symptoms of ulcerative colitis are abdominal pain and bloody diarrhea.

Patients also may experience

• anemia
• fatigue
• weight loss
• loss of appetite
• rectal bleeding
• loss of body fluids and nutrients
• skin lesions
• joint pain
• growth failure (specifically in children)

About half of the people diagnosed with ulcerative colitis have mild symptoms. Others suffer frequent fevers, bloody diarrhea, nausea, and severe abdominal cramps. Ulcerative colitis may also cause problems such as arthritis, inflammation of the eye, liver disease, and osteoporosis. It is not known why these problems occur outside the colon. Scientists think these complications may be the result of inflammation triggered by the immune system. Some of these problems go away when the colitis is treated.

What causes ulcerative colitis?

Many theories exist about what causes ulcerative colitis. People with ulcerative colitis have abnormalities of the immune system, but doctors do not know whether these abnormalities are a cause or a result of the disease. The body’s immune system is believed to react abnormally to the bacteria in the digestive tract.

Ulcerative colitis is not caused by emotional distress or sensitivity to certain foods or food products, but these factors may trigger symptoms in some people. The stress of living with ulcerative colitis may also contribute to a worsening of symptoms.

Crohn's disease

Crohn's disease causes inflammation in the small intestine. Crohn's disease usually occurs in the lower part of the small intestine, called the ileum, but it can affect any part of the digestive tract, from the mouth to the anus. The inflammation extends deep into the lining of the affected organ. The inflammation can cause pain and can make the intestines empty frequently, resulting in diarrhea.
Crohn's disease is an inflammatory bowel disease (IBD), the general name for diseases that cause inflammation in the intestines. Crohn's disease can be difficult to diagnose because its symptoms are similar to other intestinal disorders such as irritable bowel syndrome and to another type of IBD called ulcerative colitis.
Ulcerative colitis causes inflammation and ulcers in the top layer of the lining of the large intestine.
Crohn's disease affects men and women equally and seems to run in some families. About 20 percent of people with Crohn's disease have a blood relative with some form of IBD, most often a brother or sister and sometimes a parent or child.
Crohn's disease may also be called ileitis or enteritis.

What causes Crohn's disease?
Theories about what causes Crohn's disease abound, but none has been proven.
The most popular theory is that the body's immune system reacts to a virus or a bacterium by causing ongoing inflammation in the intestine.
People with Crohn's disease tend to have abnormalities of the immune system, but doctors do not know whether these abnormalities are a cause or result of the disease. Crohn's disease is not caused by emotional distress.

What are the symptoms?
The most common symptoms of Crohn's disease are abdominal pain, often in the lower right area, and diarrhea. Rectal bleeding, weight loss, and fever may also occur. Bleeding may be serious and persistent, leading to anemia. Children with Crohn's disease may suffer delayed development and stunted growth.

Diverticula

A diverticulum is a small pouch with a narrow neck that protrudes from (sticks out from) the wall of the gut. Diverticula means more than one diverticulum.
Some people are born with a diverticulum, most often from the small intestine. Most diverticula develop during later life and are more and more common with increasing age.
the symptoms of diverticular disease are due to the muscle abnormality and consist of pain, usually in the left lower part of the abdomen, often abdominal distension, an irregular bowel habit with pellet-like stools, and sometimes small quantities of blood passed with bowel actions. These symptoms are similar to those of the irritable bowel syndrome which is not surprising because both disorders, at least in part, are due to abnormal muscle function.
A diverticulum may occasionally bleed and you may pass some blood via your anus. The bleeding is usually abrupt and painless. The bleeding is due to a burst blood vessel that sometimes occurs in the wall of a diverticulum and so the amount of blood loss can be heavy.