Diverticular disease and diverticulitis

Page last reviewed: 13/07/2011

Diverticular disease and diverticulitis are two related digestive conditions. Symptoms of diverticular disease include:

  • lower abdominal (stomach) pain
  • feeling bloated

Symptoms of diverticulitis include:

  • severe abdominal pain
  • high temperature (fever) of 38ºC (100.4ºF) or above

Diverticula, diverticular disease and diverticulitis

Diverticula is the medical term that is used to describe the small pouches that stick out of the side of the large intestine (colon). Diverticula are very common and associated with ageing. It is estimated that 50% of people have diverticula by the time they are 50 years old, and 70% of people have them by the time they are 80 years old.

The majority of people with diverticula will not have any symptoms. However, 1 in 4 people with diverticula experience symptoms such as abdominal pain and diarrhoea. People who experience symptoms are said to have diverticular disease.

The diverticula can also become infected and inflamed. Inflammation of the diverticula is known as diverticulitis. Diverticulitis causes more severe symptoms than diverticular disease, such as severe pain. It carries a risk of causing serious complications, such as the colon rupturing (splitting), which can lead to an infection of the lining of the abdomen (peritonitis).

How common are diverticular disease and diverticulitis?

Diverticular disease is one of the most common digestive conditions. Like the diverticula, diverticular disease is associated with age. About 75% of people with diverticular disease will have one or more episodes of diverticulitis.

It is estimated that 30% of people who are 60 years old or more are affected by diverticular disease. This figure rises to 65% for people who are 80 years of age or more.

Both sexes are equally affected by diverticular disease and diverticulitis, although the condition is more likely to appear at a younger age (under 50) in men than in women.

Diverticular disease is often described as a 'western disease' because the rates are very high in western European and North American countries, and very low in African and Asian countries. Diet is thought to be the primary reason for this and, in particular, the fact that many people in western countries only eat a small amount of fibre. A low-fibre diet is known to be a significant risk factor for the condition.

In Ireland, the number of people who are affected by diverticular disease and diverticulitis is expected to rise over the next decade as a result of the corresponding increase in the number of people who are 60 years of age or above.


Generally, the outlook for diverticular disease is good because the symptoms can usually be controlled by including more fibre in your diet.

However, the outlook for diverticulitis is less favourable, as around 1 in 5 people will have complications that often require surgery to treat. In cases where no complications occur (uncomplicated diverticulitis), the recommended treatment is a short course of antibiotics.

If a person has repeated episodes of complicated diverticulitis, surgery to remove the affected section of the colon may be recommended as a preventative measure.

Page last reviewed: 13/07/2011

Diverticular disease

The most common symptom of diverticular disease is intermittent (stop-start) pain in your lower abdomen (stomach), usually in the lower left-hand side. The pain is often worse when you are eating, or shortly afterwards. Passing stools (faeces) and breaking wind (flatulence) may help to relieve the pain.

Other symptoms of diverticular disease include:

  • a change in your normal bowel habits, such as constipation or diarrhoea, or episodes of constipation that are followed by diarrhoea
  • bloating
  • bleeding from your rectum (back passage)


The main symptom of diverticulitis is a constant and severe pain. The pain usually starts below your belly button, before moving to the lower left-hand side of your abdomen.

In Asian people, the pain may move to the lower right-hand side of your abdomen. This is because Asian people tend to develop diverticula in a different part of their colon. The reason for this is thought to be genetic (certain genes found in Asian people may change the natural course of the condition).

Besides severe stomach pain, other symptoms of diverticulitis include:

  • a high temperature (fever) of 38ºC (100.4ºF) or above
  • a frequent need to urinate
  • pain when you urinate
  • nausea
  • vomiting
  • constipation
  • bleeding from your rectum (where solid waste is stored)

When to seek medical advice

Contact your GP as soon as possible if you think you have symptoms of diverticulitis. The sooner diverticulitis is treated with antibiotics, the lower the risk of complications developing.

If you have the symptoms of diverticular disease and the condition has previously been diagnosed, you do not usually need to contact your GP because the symptoms can be treated at home. See Diverticular disease and diverticulitis - treatment for more information.

If a diagnosis has not been confirmed, contact your GP so that they can rule out other conditions that have similar symptoms, such as irritable bowel syndrome (IBS).

Contact your GP if you have constant or heavy rectal bleeding. The bleeding is usually not painful, but if you lose too much blood you will need to go to hospital for a blood transfusion.

Page last reviewed: 13/07/2011

To better understand the causes of diverticular disease and diverticulitis, it is useful to learn about the function of the colon.

The colon

The colon plays two important roles in the process of digestion. The colon:

  • helps to remove the nutrients from the food that you eat
  • pushes undigested waste products down into your rectum (the end of the large bowel) and out of your anus (back passage) where they are expelled from your body as stools (faeces)

The structure of your colon is similar to that of a tyre. It consists of a flexible inside layer of tissue that is covered by a firmer, tougher layer of muscle.

Lack of fibre

Not eating enough fibre is thought to be a main reason why diverticula (the small pouches that stick out of the side of the colon) develop.

Fibre makes your stools softer and larger so that less pressure is needed by your colon to push them out of your body. Eating low-fibre food produces small, hard stools. These are more difficult for the muscles of your colon to move, and will cause you to strain.

The pressure of moving the hard, small pieces of stools through your colon creates weak spots in the outside layer of muscle. This allows the inner layer to squeeze through these weak spots, creating the diverticula.

There is no clinical evidence to fully prove the link between fibre and diverticula, but the circumstantial evidence is compelling.

For example, in parts of the world where high-fibre diets are common, such as Africa and South Asia, cases of of diverticula and diverticula disease are almost non-existent. However, in western countries, where many people do not eat enough fibre, diverticula and diverticula disease are much more common.

Diverticular disease

It is not known why only 1 in 4 people with diverticula go on to have the symptoms of diverticula disease.

However, a number of risk factors have been identified that appear to increase your risk of developing diverticular disease. These include:

Exactly how these factors lead to the increased risk of developing diverticular disease is unclear.


Diverticulitis is caused by an infection of one or more of the diverticula (small pouches that stick out of the side of the large intestine).

It is thought that an infection can develop when a hard piece of stool (faeces) gets trapped in one of the pouches. This gives the bacteria in the stool the chance to multiply and spread, triggering an infection.

Page last reviewed: 13/07/2011

Diverticular disease

Diverticular disease can be difficult to diagnose from the symptoms alone because there are many other conditions that cause similar symptoms, such as irritable bowel syndrome (IBS), a common but poorly understood condition that causes inflammation of the bowel.

Therefore, as a first step, your GP may recommend that you have some blood tests. These tests cannot diagnosis diverticular disease but they can help to rule out other conditions.


To confirm the presence of diverticula (small pouches in the side of the colon) the inside of your large intestine (colon) will be looked at. One way of doing this is through a technique known as a colonoscopy.

During a colonoscopy, a thin tube with a camera at the end (a colonoscope) is placed through your rectum and guided into your colon. Before the procedure begins, you will be given a laxative to clear out your bowels.

Colonoscopies are not painful because they are done under local anaesthetic (medication that numbs the surrounding area). However, you may feel a little discomfort during the procedure.

Barium enema X-ray

Another technique for confirming the presence of diverticula is a barium enema X-ray. Barium is a liquid that shows up on X-rays. It is used to coat the inside surface of organs that do not show up on X-ray, such as the colon.

As with a colonoscopy, you will be given a laxative to clear out your bowels before you have a barium enema X-ray.

During the procedure, a tube is inserted into your rectum. The barium liquid is squirted into the tube and passed up into your rectum. A series of X-rays are then taken. Although the procedure is not painful, some people may find it embarrassing.

For a few days after having a barium enema X-ray, your stools will appear white and discoloured due to the barium passing out of your body. It is nothing to worry about.


If you have had a previous history of diverticular disease, your GP will usually be able to make a diagnosis of diverticulitis by carrying out a physical examination and asking you about your symptoms and medical history. A blood test may be taken because a high number of white blood cells can indicate the presence of infection.

Further tests will be needed if you have no previous history of diverticular disease. This is necessary to confirm the diagnosis and to rule out any other possible conditions, such as gallstones or a hernia.

A barium enema X-ray may be used, as well as a computerised tomography (CT) scan. A CT scan takes a series of X-ray scans, which are then reassembled by a computer to build up a more detailed 3-D image of the inside of your body.

A CT scan may also be used if your symptoms are particularly severe. This is to check whether the infection has spread to other parts of your body, or whether a complication, such as an abscess (a pus-filled cavity in the tissue), has occurred.

Page last reviewed: 13/07/2011

Diverticular disease

Most cases of diverticular disease can be treated at home. The over-the-counter (OTC) painkiller, paracetamol, is recommended to help relieve your symptoms.

The type of painkillers known as non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, are not recommended because they may upset your stomach and increase your risk of internal bleeding.

Eating a high-fibre diet may initially help to control and resolve your symptoms of diverticular disease. Some people will notice an improvement after a few days, although it can take around a month for you to fully feel the benefits. See Diverticular disease and diverticulitis - prevention for more information and advice about diet.

If you are having symptoms of constipation, you may be given a bulk-forming laxative. These can cause flatulence (wind) and bloating. Drink plenty of fluid to prevent any obstruction in your digestive system.

Heavy or constant rectal bleeding occurs in about 1 in 3 cases of diverticular disease. This can happen if the blood vessels in your large intestine (colon) are weakened by the diverticula, making them vulnerable to damage. The bleeding is usually painless, but losing too much blood can be potentially serious.

If you have heavy rectal bleeding, you may need to be admitted to hospital so that you can be given a blood transfusion.


Treatment at home

If you have mild diverticulitis, the condition can often be treated at home. Your GP will prescribe antibiotics for the infection, and you should take paracetamol for the pain. If antibiotics are prescribed for you, it is important that you finish the complete course even if you are feeling better.

Some types of antibiotics that are used to treat diverticulitis can cause side effects in some people.

Possible side effects include:

  • drowsiness (do not drive if you have this side effect)
  • nausea
  • vomiting
  • diarrhoea 

Also, some antibiotics may react unpredictably if they are taken with alcohol. Therefore avoid drinking alcohol until you have finished taking your course of antibiotics.

Antibiotics have been known to cause the contraceptive pill and patch to fail. Therefore use an additional form of contraception, such as a condom, when taking antibiotics, and for seven days afterwards. Your GP can give you advice about the types of antibiotics that are likely to cause a problem.

Your GP may recommend that you stick to a fluid-only diet for a few days until your symptoms improve. This is because trying to digest solid foods may make your symptoms worse. You then gradually introduce solid foods over a two or three day period.

Treatment at hospital

If you have more severe diverticulitis, you may need to go to hospital. Hospital treatment is usually recommended if:

  • your pain cannot be controlled using paracetamol
  • you are unable to drink enough fluids to keep you hydrated
  • you are unable to take oral antibiotics (tablets)
  • your general state of health is poor
  • you have a weakened immune system
  • your GP suspects complications
  • your symptoms fail to improve after two days (48 hours) of treatment at home

If you are admitted to hospital for treatment, you are likely to receive injections of antibiotics and be kept hydrated and nourished using an intravenous drip (a tube that is directly connected to your vein). Most people start to improve within two to three days.


In the past, surgery was usually recommended as a preventative measure for people who had two episodes of uncomplicated diverticulitis,. It was believed that this would reduce their risk of developing serious complications in the future, such as peritonitis.

But nowadays most surgeons do not recommend surgery. This is because research has found that the risks of complications associated with having two episodes of uncomplicated diverticulitis are lower than were previously thought. For example, one study estimated that it would take 18 operations to prevent just one case of serious complications.

The surgery itself is also not risk free. Complications that lead to death can occur in 1 in every 100 cases. As with any form of medical treatment, surgery is only recommended if it is felt that the benefits outweigh the risks.

The benefits and risks of surgery are currently determined on a case-by-case basis, as a 'one size fits all' type of recommendation is considered unhelpful. Factors that may cause surgery to be recommended include:

  • having a history of serious complications arising from a previous episode of diverticulitis
  • having symptoms of diverticular disease from at a young age (it is thought that the longer you live with diverticular disease, the greater your chances of having a serious complication)
  • having a weakened immune system or other underlying factors that make you more vulnerable to the effects of infection


Surgery for diverticulitis involves removing the affected section of your colon. This is known as a colectomy. There are two ways that a colectomy can be performed:

  • an open colectomy, where the surgeon makes a large incision (cut) in your abdomen and removes a section of your colon
  • laparoscopic colectomy - a type of 'keyhole surgery' where the surgeon makes a number of small incisions in your abdomen and uses special instruments that are guided by a camera to remove a section of colon

Open colectomies and laparoscopic colectomies are thought to be equally effective in treating diverticulitis, and have a similar risk of complications. Laparoscopic colectomies have the advantage of having a faster recovery time, and they cause less post-operative pain.

Laparoscopic colectomies are a relatively new technique and may only be available at specialist surgical centres. There may also be a longer waiting time for this type of surgery.

Stoma surgery

In some cases, the surgeon may decide that your colon needs to heal before it can be reattached, or that too much of your colon has been removed to make reattachment possible.
In such cases, it is necessary to find a way of removing wasting materials from your body without using all of your colon. This is done using stoma surgery.

Stoma surgery involves the surgeon making a small hole in your abdomen that is known as a stoma. There are two ways that stoma surgery can be carried out. These are explained below.

  • An ileostomy, where a stoma is made in the right-hand side of your abdomen (stomach). Your small intestine is separated from your colon and connected to the stoma, and the rest of the colon is sealed. You will need to wear a pouch that is connected to the stoma to collect waste material.
  • A colostomy, where a stoma is made in your lower abdomen and a section of your colon is removed and connected to the stoma. As with an ileostomy, you will need to wear a pouch to collect waste material.

In most cases, the stoma will be temporary and can be removed once your colon has recovered from the effects of the surgery. This will usually take at least nine weeks.

If a large section of your colon is affected by diverticulitis and needs to removed, you may need to have a permanent ileostomy or colostomy.

Results of surgery

In general terms, surgery is usually successful, although it does not achieve a complete cure in all cases. Following surgery, an estimated 8% of people will have a recurrence of the symptoms of diverticular disease and diverticulitis. 

Page last reviewed: 13/07/2011

Complications of diverticulitis affect 1 in 5 people with the condition. Those most at risk of developing complications are younger people (under 50 years of age) who need multiple admissions to hospital due to the severity of their symptoms.

Some of the complications that are associated with diverticulitis are discussed below.


The most common complication of diverticulitis is the development of an abscess inside the large intestine (colon). An abscess is a pus-filled cavity or lump in the tissue. Abscesses are usually treated with a technique known as percutaneous abscess drainage (PAD).

A radiologist (a specialist in the use of imaging equipment, such as computerised tomography scans) will use an ultrasound or CT scanner to locate the site of the abscess.

A fine needle that is connected to a small tube will be passed through the skin of your abdomen (stomach) and into the abscess. The tube is then used to drain out the pus from the abscess. A PAD is performed under a local anaesthetic, so it is not particularly painful.

Depending on the size of the abscess, the procedure may need to be repeated several times before all of the pus has been drained away. If the abscess is very small - usually less than 4cm (1.5in) - it may be possible to treat it using antibiotics.

See the Health A-Z topic about Abscess for more information.


After an abscess, a fistula is the second most common complication of diverticulitis. Fistulas are abnormal tunnels that connect two parts of the body together, such as your intestine and your abdominal wall or bladder.

If infected tissues come into contact with each other they can stick together. After the tissues have healed, a fistula may form. Fistulas can be potentially serious as they can allow bacteria in your large intestine (colon) to travel to other parts of your body, triggering infections, such as an infection of the bladder (cystitis).

Fistulas are usually treated with surgery to remove a small section of the colon that contains the fistula.

See the Health A-Z topic about Anal Fistula for more information.


In rare cases, an infected diverticula (pouch in your colon) can rupture (split), spreading the infection into the lining of your abdomen (stomach). An infection of the lining of the abdomen is known as peritonitis.

Peritonitis can be life-threatening, and requires immediate treatment with antibiotics. Surgery may also be required to repair any damage and to drain any pus that has built up.

Intestinal obstruction

If the infection has badly scarred your colon, your colon may become partially or totally blocked. A totally blocked colon is a medical emergency because without immediate medical help, the tissue of your colon will start to decay and eventually rupture (split), leading to peritonitis.

A partially blocked colon is not as urgent a situation as a fully blocked one, but treatment is still needed. If left untreated, it will affect your ability to digest food. It will also cause you considerable pain.

In some cases, the blocked part of your colon can be removed during a colon resection (surgically removing the affected part of the colon). However, if the scarring and blockage is more extensive, a temporary or permanent colostomy may be needed.

Page last reviewed: 13/07/2011

Eating a high-fibre diet may help to prevent diverticular disease, and it may improve your symptoms.

Your diet should be balanced and include at least five daily portions of fruit and vegetables, plus whole grains. Adults should aim to eat between 18g (0.6oz) to 30g (1.05oz) of fibre a day, depending on their height and weight. Your GP can provide a more specific target, based on your individual height and weight.

It is recommended that you gradually increase your fibre intake over the course of a few weeks. This will help to prevent the side effects associated with a high-fibre diet, such as bloating and flatulence (wind).

Also drink plenty of fluids because this will help to prevent any side effects.

Once you have reached your fibre target, stick to it for the rest of your life if possible. The fibre found in certain fruits and vegetables is thought to be more effective in preventing diverticular disease that the fibre that is found in cereals. The reason for this is uncertain.

Good sources of fibre in vegetables (plus the amount of fibre that is found in typical portions) include:

  • red kidney beans - three tablespoons contain 5.4g of fibre
  • baked beans - a 100g can contains 3.7g of fibre
  • peas - three heaped tablespoons contain 3.6g of fibre
  • brussel sprouts - eight sprouts contain 3.3g of fibre
  • potatoes - one medium-sized potato contains 2.4g of fibre

Good sources of fibre in fruit (plus the amount of fibre that is found in typical portions) include:

  • avocado pear - one medium-sized avocado pear contains 4.9g of fibre
  • pear (with skin) - one medium-sized pear contains 3.7g of fibre
  • orange - one medium-sized orange contains 2.7g of fibre
  • apple - one medium-sized apple contains 2g of fibre
  • banana - one medium-sized banana contains 1.7g

Fibre supplements - usually in the form of sachets of powder that you mix with water - are also available from most pharmacists and health food shops.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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