Diverticulosis occurs when small defects in the muscle of the wall of the large intestine or colon allow small pockets or pouches (diverticula) to form.

Diverticulitis is infection or inflammation of these abnormal pouches. Together, these conditions are called diverticular disease.

Despite having some symptoms in common, diverticular disease isn’t associated with more serious conditions, such emergency, requiring immediate medical attention and, frequently, admission to hospital. Mild attacks can be treated at home, but should always be assessed promptly.

Causes of diverticular disease

Diverticulosis is extremely common. Old age and diet may be the most important risk factors. More than half of all adults over the age of 70 have the condition. Most of these people are unaware that they have diverticulosis.

Diverticulosis is less common in people under 50.

Studies appear to show that diverticulosis became more common in the 20th century.

It is also more common in ‘Western’ nations including North America, Europe and Australia.

It is less common in Asia and very uncommon in Africa.

Discovery of these facts led to the theory that the low-fibre diet common in Western nations may be important. Animal studies show that this theory is possible. It has also been shown that vegetarians less commonly develop diverticulosis.

Exactly how a low-fibre diet may cause diverticulosis is not known.

There may also be genetic causes.

It is interesting that Western people develop diverticulosis in the last third of the colon, while people in Asian countries – such as Japan, Taiwan and Singapore – generally develop diverticulosis in the first section of the colon. In the Japanese population living in Hawaii, the risk of diverticulosis is higher than those living in Japan. However, when diverticulosis develops in these people, it is still in the ‘Japanese’ location – the first third of the colon.

Diverticulitis seems to occur when a small puncture develops in the diverticular wall. This causes a small infection to develop, often forming an abscess.

Symptoms of diverticulosis

Diverticulosis is usually asymptomatic (has no symptoms). However, when many diverticula (pouches) are present, the normal smooth working of the bowel can be affected.

This may cause a range of symptoms including:

• Abdominal pain and bloating

• Constipation and diarrhea

• Flatulence

• Blood in the faces – this is usually minor, but bleeding can sometimes be heavy if a diverticulum gets inflamed or is near a blood vessel.

• Anemia from repeated bleeding may occur.

Many of these symptoms are similar to those of bowel cancer. Diverticulosis is more common, so these symptoms may be more likely to be due to diverticulosis than cancer. However, a specialist will usually assess these symptoms – your doctor will refer you.

Symptoms of diverticulitis include:

• Sharp pain, often located at a specific point – for example, in the lower left half of the abdomen

• Fever

• Distension (bloating) of the abdomen

Nausea and vomiting