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Diverticula are pouches that form in the wall of the large intestine, particularly where small blood vessels penetrate the bowel wall. Diverticula are very common in Western civilization; 30% of the population have diverticula by age 50, a figure that increases to 65% with diverticula or diverticulosis by the age of 85.

There is often confusion between the terms ‘diverticulosis’ and ‘diverticulitis’. Diverticulosis merely refers to the presence of diverticula; diverticulitis includes the complication of inflammation in the diverticula. The suffix ‘itis’ in Latin means ‘inflammation’; therefore diverticul-itis means inflammation of the diverticula.



About 70% of individuals never develop any symptoms from the diverticula. In 15%–25% of individuals, inflammation develops in the diverticula (diverticulitis). In 5%–10% of individuals, there is bleeding from a blood vessel associated with the diverticula.


There is a public perception that diverticular disease or diverticulosis causes symptoms in spite of the fact that it never does so in most patients. This misapprehension may be due to symptoms of Irritable Bowel Syndrome (IBS) being mistakenly attributed to diverticulosis. IBS (common symptoms are bowel problems and abdominal pain) occurs in 10%–20% of the population, which includes those individuals with diverticulosis. Patients with both conditions are not always aware that symptoms stem from their IBS and are not caused by the co-existing diverticulosis.  


Sometimes a hard piece of stool can become lodged within a diverticulum. When this occurs, inflammation can occur. Common symptoms are pain in the lower abdomen, changes in the bowels (either diarrhea or constipation), nausea, vomiting or even symptoms related to urination. There often is fever. Individuals from Asian cultures commonly feel the abdominal pain on the right lower side, while individuals from ‘the West’ usually experience pain in the left lower abdomen. The reasons for this difference are unclear.

Diverticular Bleeding

Sometimes, bleeding can occur when the small blood vessel or artery associated with a diverticulum ruptures. Typically in such cases there is no abdominal pain, unlike diverticulitis which is usually associated with abdominal pain. About half of patients with diverticulosis  will have intermittent episodes of seeing either maroon or bright red blood in the toilet.




Diverticulosis is often diagnosed incidentally when tests are being done to diagnose other problems. Tests such as a CT scan or colonoscopy can diagnose the presence of diverticula.


Diverticulitis is diagnosed from an occurrence of symptoms, and from blood tests and imaging studies such as a CT scan that are consistent with this diagnosis.

Diverticular Bleeding

Diverticular bleeding is painless; there is no abdominal pain associated with it. It is rare for bleeding to co-exist with acute diverticulitis. Individuals with bleeding are most often diagnosed by colonoscopy.

Individuals who have had complications from diverticulosis, such as diverticular bleeding or diverticulitis should have a colonoscopy at some point to be sure there is nothing else going on, particularly the development of colon cancer.




Individuals with diverticulosis have no symptoms and do not require treatment. We do, however know that individuals with low dietary fiber intake tend to develop and have more issues with diverticular disease. Increased dietary fiber is therefore often recommended. The theory is that higher dietary fiber intake will result in fewer diverticula forming over time, making an individual less likely to have issues associated with them.


Historically, individuals with diverticula have been told to avoid foods with seeds or nuts. Although this makes intuitive sense (that the seeds could get wedged in the diverticula) there is no scientific evidence that eating seeds or nuts causes problems in individuals with diverticula. In spite of the lack of supporting evidence this is a commonly held belief and is part of medical folklore.


The treatment of diverticulitis depends on its severity. Diverticulitis is mild in 75% of individuals and that they can be treated at home with antibiotics and a fluid diet. It is considered to be more severe in the remaining 25% of individuals; when pain is severe, they are unable to tolerate fluids or they have complications including the development of an abscess (a collection of pus), a blockage of the colon, severe inflammation throughout the abdomen (peritonitis) or an abnormal connection between the bowel and another organ such as the bladder or vagina (fistula). Individuals with more severe diverticulitis need to be hospitalized and put on antibiotics and fluids intravenously (through a vein). With time, symptoms will usually settle down but in some individuals surgery is required and the diseased bowel will need to be removed.

In individuals who are quite ill, surgery is usually done in two stages. First the section of diseased bowel is removed and the individual has a temporary colostomy for about 3 months, allowing time for antibiotics to work and for the inflammation to settle down and heal. A colostomy is an opening in the abdomen where the bowel is connected to the skin and a bag is attached to collect stool from the colon. Approximately 3 months afterwards the second part of the surgery is performed; the colostomy is brought down, the colon is reconnected and the opening to the skin is closed. After this procedure the patient can empty the bowels as normal through the rectum.

Diverticular Bleeding

Fortunately diverticular bleeding stops on its own in most individuals. Sometimes, the bleeding can be stopped during a colonoscopy, or with an angiography (a special test during which dye is injected into the artery to see the origin of the bleeding). If the bleeding does not stop with these measures the diseased bowel sometimes has to be removed with surgery.



Most individuals with diverticulosis will never experience any problems.

In individuals with diverticulitis, 85% will respond to medication and only 15% will require surgical intervention. In individuals who have an episode of diverticulitis that settles down without surgery, a further 33% (a third) will have another episode of diverticulitis.

In 80% of individuals who have diverticular bleeding it will stop on the initial presentation, only 20% having a future episode of bleeding.