What is diverticulitis?

Diverticulitis, also called diverticular disease, is a disease of the diverticula in the gut (intestine). The diverticula are pouches that can occur in the intestine, a condition known as diverticulosis. These pouches are formed when the wall of the intestine protrudes though a weak area in the muscle surrounding the intestine. Diverticula usually occur in the large intestine (or colon), but can happen in the small intestine.

Diverticulitis is actually inflammation of the diverticula. Symptoms vary between people; patients may feel unwell and have gut symptoms such as pain (particularly on the lower left side of your abdomen), bloating, and irregular bowel movements. Some patients may be constipated, others have diarrhoea, and some have alternating constipation and diarrhoea. Indeed, symptoms of diverticulitis may closely resemble irritable bowel syndrome.

The large majority of people have no symptoms, and many people with diverticula are unaware that they have the condition. One-fifth of people develop symptoms, and complications are fairly uncommon in those who have symptoms. Rarely, severe inflammation occurs leading to peritonitis and narrowing or blockage of the colon.

What causes diverticulitis?

Diverticulitis is thought to result from eating a refined diet that is low in fibre. Fibre is the part of food that cannot be digested. It passes through our intestine, forming stools (faeces) that are easy to pass and preventing constipation. When the diet is low in fibre, small stools are formed that are difficult to pass. Constipation requires the gut to exert great force to push the stools through the gut. Over time, this pressure pushes the intestine wall through its outer layers, forming the pouches that are characteristic of diverticulitis. Inflammation of the diverticula occurs when some of the faeces get trapped in the diverticula, which allows bacteria to grow there and leads to infection.

Who is at risk of diverticulitis?

Diverticulitis is a widespread condition. It is more common in the developed Western countries and less common in the developing countries, with between one-third and one-half of Western Europe and North America populations and up to one quarter of Asian and African populations having the condition in their lifetime. Notably, the numbers of cases of diverticulitis increase as countries shift to a westernised diet and lifestyle. Additionally, the chance of having diverticulitis increases with age. While age-related changes in gut motility and nerves may play a role, it is not so much your age itself that is the problem but the increased time that the intestinal wall is exposed to pressure.

How can I reduce the risk of diverticulitis?

Since lack of dietary fibre plays an important role in the development of diverticulitis, the best way to avoid diverticulitis is to increase your consumption of whole grain cereals (wholemeal bread, pasta, and brown rice), fruit, and vegetables over the long term. However, people with diverticulitis symptoms react differently to the various types of dietary fibre, and no diet will suit everybody. Some benefit from soluble fibre (fruit and vegetables). Insoluble fibre (grains and cereals) can cause pain and bloating, and bran is not generally recommended.

When should a doctor be contacted?

You are advised to see a doctor if you develop severe pain and soreness in your lower abdomen, particularly if you think you have a raised temperature. This might indicate that you have inflammation of the diverticula, and that you have either developed diverticulitis or have an exacerbation of the condition.

How is diverticulitis diagnosed?

The doctor will need to look at your intestine to make a positive diagnosis. This is done by a procedure called colonoscopy, whereby a thin tube with a camera attached (a colonoscope) is passed through your anus and into your intestine. Another method is by a barium enema, which highlights the intestine so that it can be visualised on x-ray. Because many people have diverticula but no symptoms, the doctor will look for anything abnormal that could be the cause of your symptoms.

How is diverticulitis treated?

If you have diverticula but no symptoms, you do not need treatment but may be advised to eat a diet high in fibre to prevent the future development of symptoms.

Most patients with diverticulitis without complications are treated successfully with oral antibiotics if they experience a flare up of symptoms. There is no exact treatment for the symptoms of pain, bloating, and irregular bowel movements. Dietary modification as described above may help, and there are some medicines (such as ispaghula and methylcellulose) that provide bulk and help relieve constipation. Antispasmotic medicines may be prescribed to control gut spasms. However, if your symptoms are severe, hospital admission and surgery to remove the part of the intestine with diverticula may be necessary to prevent further exacerbations and later complications.

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