Diverticular disease and diverticulitis

Diverticular disease and diverticulitis are two related conditions of the digestive system. Both affect the large intestine (the colon).

In diverticular disease, small bulges or pockets, called diverticula, form in the lining of the intestine. Diverticulitis is what happens when these pockets become inflamed or infected.

Symptoms of diverticular disease include:

• lower abdominal pain
• feeling bloated

Most people who have diverticula never notice any symptoms at all, and this is known as diverticulosis.

Symptoms of diverticulitis tend to be more serious. They include:

• more severe abdominal pain, especially on the left side
• high temperature (fever) of 38C (100.4F) or above
• diarrhoea or frequent bowel movements

Diverticula is the medical term for small bulges that stick out of the side of the large intestine (colon).

They're common, and they tend to come with ageing. The large intestine gets weaker as you get older, and the pressure of hard stools passing through it is thought to cause the bulges to form. You can read more about the causes of diverticula separately.

It's estimated that 5% of people have diverticula by the time they are 40 years old, and at least 50% of people have them by the time they are 80 years old.

About 1 in 4 people who develop diverticula will have symptoms, such as abdominal pain. When symptoms do appear, doctors call it diverticular disease.

Diverticulitis is an infection that happens when bacteria get trapped inside one of the bulges, and it brings on more severe symptoms.

It can lead to complications, such as an abscess next to the intestine.

A high-fibre diet can often ease the symptoms of diverticular disease. Paracetamol can help with the pain, but other painkillers such as aspirin or ibuprofen are not recommended for regular use because they can upset the stomach. If paracetamol alone isn't working, speak to your doctor.

Mild diverticulitis can usually be treated at home with antibiotics prescribed by your doctor. More serious cases may need treatment in hospital, both to prevent complications and to treat them.

Surgery to remove the affected section of the intestine is sometimes recommended if there have been serious complications, although this is rare.

Diverticular disease is one of the most common digestive conditions. Men and women are affected equally, by both diverticular disease and diverticulitis. The one difference is age, because men are more likely than women to develop it younger, under 50. Symptoms of diverticulitis are most likely to appear in people over 70 years old.

People often call diverticular disease a "Western disease", because rates are high in European and North American countries and low in African and Asian countries. A mix of genetics and diet is thought to explain this, along with the fact that people in Western countries tend to eat less fibre.

Fibre seems to make a real difference. People aged 50 to 70 who eat a high-fibre diet (25g a day) have a 40% lower chance of being admitted to hospital with complications of diverticular disease, compared with others in their age range who eat the least fibre.

If you have diverticular disease or diverticulitis, you may notice abdominal pain, bloating and a change in your normal bowel habits.

Finding out that you have diverticula can be worrying, especially if they were picked up by chance during a camera test of the bowel (colonoscopy) or a CT scan done for some other reason. Try not to be alarmed. If you have never had abdominal pain or bouts of diarrhoea, there is a 70% to 80% chance that you will never have any symptoms from them.

Diverticula are extremely common over the age of 70, and they do not increase your risk of cancer. A high-fibre diet is thought to be likely to reduce the risk of any symptoms developing.

The most common symptom of diverticular disease is pain in your lower abdomen (stomach) that comes and goes, usually on the lower left-hand side. The pain is often worse while you are eating, or shortly afterwards. Passing stools and breaking wind (flatulence) may ease it.

There are other long-term symptoms too:

• a change in your normal bowel habits, such as constipation or diarrhoea, or episodes of constipation that are followed by diarrhoea. A classic pattern is several trips to the toilet in the morning to pass stools like 'rabbit pellets'
• bloating

Diverticular disease can also cause bleeding of dark purple blood from your rectum (back passage). This usually comes after cramping pain that feels like diarrhoea, and it often leads to admission to hospital. Fortunately, it is an uncommon complication.

Diverticular disease does not cause weight loss. So if you are losing weight, seeing blood in your stools or having frequent bowel changes, see your doctor.

Diverticulitis has most of the same symptoms as diverticular disease (see above). The difference is the pain. With diverticulitis it is constant and severe, not on and off. You are most likely to get it if you have had symptoms of diverticular disease before, and it builds up over a day or 2.

Other symptoms of diverticulitis can include:

• a high temperature (fever) of 38C (100.4F) or above
• a general feeling of being tired and unwell
• feeling sick (nausea) or being sick (vomiting)

The pain usually starts below your belly button and then moves 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 instead. This is because East Asian people tend to develop diverticula in a different part of their colon for genetic reasons.

If you think you have symptoms of diverticulitis, see a doctor as soon as possible.

If you've already been diagnosed with diverticular disease and your symptoms come back, you don't usually need to see a doctor, because the symptoms can be treated at home. Read more about the treatment of diverticular disease.

If you haven't been diagnosed with the condition, see a doctor so they can rule out other conditions with similar symptoms, such as:

• a stomach ulcer
• pancreatitis
• cholecystitis
• bowel cancer

Irritable bowel syndrome (IBS) can also cause symptoms similar to those of diverticular disease.

Diverticular disease happens when small bulges (diverticula) form in the large intestine and become inflamed. If any of these bulges gets infected, you develop the symptoms of diverticulitis.

Doctors don't know exactly why diverticula develop, but they are linked with not eating enough fibre.

Fibre makes your stools softer and larger, so your large intestine needs less pressure to push them out of your body.

When hard, small pieces of stool have to be moved along, the pressure creates weak spots in the outer layer of muscle. The inner layer (mucosa) can then squeeze through these weak spots, and that is how the diverticula form.

There is currently no clinical evidence that fully proves the link between fibre and diverticula. Still, both diverticular disease and diverticulitis are much more common in Western countries, where many people do not eat enough fibre.

Doctors don't know why only 1 in 4 people with diverticula go on to have symptoms of diverticulitis. Diverticular disease may be a form of chronic low-level diverticulitis. Its symptoms are very similar to those of irritable bowel syndrome (IBS), and the two may overlap.

Still, some factors seem to raise your risk of developing diverticular disease:

• smoking
• being overweight or obese
• having a history of constipation
• use of non-steroidal anti-inflammatory drugs (NSAIDs) painkillers, such as ibuprofen or naproxen
• having a close relative with diverticular disease, especially if they developed it under the age of 50

Exactly how these lead to diverticular disease is unclear.

Diverticulitis happens when one or more of the diverticula (the small pouches in the gut wall) become infected.

It's thought the infection starts when a hard piece of stool or undigested food gets trapped in one of these pouches. The bacteria in the stool then have the chance to multiply and spread, and that sets off the infection.

Diverticular disease can be hard to diagnose from symptoms alone, because other conditions cause similar symptoms. Irritable bowel syndrome (IBS) is one example.

As a first step, your doctor may suggest blood tests to rule out other conditions, such as coeliac disease (a condition caused by an abnormal immune response to gluten) or bowel cancer.

In some cases, you may be offered treatment for IBS and diverticular disease at the same time.

To make sure there isn't a more serious cause behind your symptoms, your doctor may send you for a colonoscopy. In this test, a thin tube with a camera at the end (a colonoscope) is put into your rectum and guided into your colon. You'll be given a laxative before the procedure begins, to clear out your bowels.

A colonoscopy is not usually painful, but it can feel uncomfortable. You may be offered painkilling medicine and a sedative beforehand, which help you relax and reduce any discomfort.

Another way to confirm diverticula is a computerised tomography scan, or CT scan. It uses X-rays and a computer to build up detailed pictures of the inside of your body.

Just as with a colonoscopy, you'll be given a laxative before the scan to clear out your bowels.

A colonography scan is a little different from a regular CT scan. A tube is put into your rectum and used to pump some air up into it. The scan is then taken twice, once with you lying on your front and once lying on your back.

You may need an injection of contrast dye before the scan, but not always.

A doctor can usually diagnose diverticulitis from your symptoms and a physical examination, as long as you have had diverticular disease before. They may also take a blood test, because a high number of white blood cells points to infection. When the symptoms are mild, the doctor will treat you at home and you should recover within 4 days.

Further tests will be needed if you have never had diverticular disease.

You may be unwell enough that the doctor sends you to hospital for blood tests and other investigations. These look for complications of diverticulitis and rule out other conditions, such as gallstones or a hernia.

An ultrasound scan may be used, and a CT scan as well.

A CT scan may also be used when your symptoms are particularly severe. It checks whether a complication, such as a perforation or an abscess, has occurred.

What treatment you need for diverticular disease or diverticulitis depends on how severe your symptoms are.

Most cases of diverticular disease can be treated at home.

Paracetamol, which you can buy over the counter, is recommended to help relieve your symptoms. Painkillers known as non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, are not recommended. They may upset your stomach and increase your risk of internal bleeding.

Eating a high-fibre diet may help to control your symptoms at first. Some people notice an improvement after a few days, although it can take around a month to feel the full benefit.

If you have constipation, you may be given a bulk-forming laxative. These can cause flatulence (wind) and bloating, so drink plenty of fluids to prevent any obstruction in your digestive system.

Heavy or constant rectal bleeding occurs in about 1 in 20 cases of diverticular disease. It can happen when the blood vessels in your large intestine (colon) are weakened by the diverticula, which makes them vulnerable to damage. The bleeding is usually painless, but losing too much blood can be potentially serious and may need a blood transfusion.

Apart from the amount of blood, these are signs that you may be bleeding heavily:

• feeling very dizzy
• mental confusion
• pale clammy skin
• shortness of breath

If you suspect that you (or someone in your care) is bleeding heavily, seek immediate medical advice. Contact your doctor at once.

Mild diverticulitis can often be treated at home. Your doctor will prescribe antibiotics for the infection, and you should take paracetamol for the pain. Finish the complete course of antibiotics, even if you are feeling better.

Some of the antibiotics used for diverticulitis can cause side effects in some people, including vomiting and diarrhoea.

Your doctor may suggest 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. Over the next 2 or 3 days, you can gradually bring solid foods back.

During the 3 to 4 days of recovery, a low-fibre diet is suggested, until you return to the preventative high-fibre diet. The reason is to reduce the amount of faeces (poo) your large bowel has to deal with while it is inflamed.

If you have not been diagnosed with diverticular disease before, your doctor may refer you for a test such as a colonoscopy or CT colonography once the symptoms have settled.

If your diverticulitis is more severe, you may need to go to hospital. This is more likely if:

• your pain cannot be controlled using paracetamol
• you are unable to drink enough fluids to keep yourself hydrated
• you are unable to take antibiotics by mouth
• your general state of health is poor
• you have a weakened immune system
• your doctor suspects complications
• your symptoms fail to improve after 2 days of treatment at home

If you are admitted to hospital, you are likely to get antibiotics as injections. You will also be kept hydrated and nourished through an intravenous drip (a tube connected directly to your vein). Most people start to improve within 2 to 3 days.

In the past, doctors recommended surgery for people who had 2 episodes of diverticulitis, as a precaution to stop complications before they happened. That is no longer the advice. Studies have found that in most cases the risks of serious complications from surgery, estimated at around 1 in 100, usually outweigh the benefits.

There are some exceptions, though:

• if you have a history of serious complications arising from diverticulitis
• if you have symptoms of diverticular disease from a young age (it is thought the longer you live with diverticular disease, the greater your chances of having a serious complication)
• if you have a weakened immune system or are more vulnerable to infections

If surgery is being considered, talk through both the benefits and the risks carefully with the doctor in charge of your care.

In rare cases, a severe episode of diverticulitis can only be treated with emergency surgery. This happens when a hole (perforation) has developed in the bowel. It is uncommon, but it causes very severe abdominal pain, and that needs an emergency trip to hospital.

Surgery for diverticulitis means removing the affected section of your large intestine. This operation is called a colectomy. It can be done in 2 ways:

• an open colectomy, where the surgeon makes a large incision (cut) in your abdomen (stomach) and removes a section of your large intestine
• a laparoscopic colectomy, a type of "keyhole surgery", where the surgeon makes a number of small incisions in your abdomen and removes a section of large intestine using special instruments guided by a camera

Both kinds of colectomy are thought to work equally well for diverticulitis, and the risk of complications is similar. People who have a laparoscopic colectomy tend to recover faster and have less pain after the operation.

If you need emergency surgery because the bowel has perforated, the operation is more likely to be open, and you may end up with a stoma.

Sometimes the surgeon decides that your large intestine needs time to heal before it can be reattached. In other cases, too much of the large intestine has been removed to make reattachment possible. When this happens, stoma surgery gives your body a way to get rid of waste without using all of your large intestine. People call it "having a bag", because a bag is stuck to the skin on your belly and the faeces (poo) collect in it.

In stoma surgery, the surgeon makes a small hole in your abdomen. This hole is called a stoma. There are 2 ways the operation can be done.

An ileostomy is where the stoma is made on the right-hand side of your abdomen. Your small intestine is separated from your large intestine and connected to the stoma, and the rest of the large intestine is sealed. You will need to wear a pouch connected to the stoma to collect waste material (poo).

A colostomy is where the stoma is made in your lower abdomen. A section of your large intestine is removed and the rest is connected to the stoma. As with an ileostomy, you will need to wear a pouch to collect waste material.

In most cases the stoma is temporary, and it can be removed once your large intestine has recovered from the surgery. This depends on the situation when you had the operation. If it was an emergency operation, you may need a few months to recover before you have surgery to reverse the stoma.

You may need a permanent ileostomy or colostomy if a large section of your large intestine is affected by diverticulitis and has to be removed. The same applies if you have multiple other conditions that make major surgery a risk.

Planned (non-emergency) surgery for diverticular disease and diverticulitis usually works well, though it doesn't cure everyone. After the operation, an estimated 1 in 12 people will have their symptoms come back.

If you need the operation in an emergency, how well it goes depends on how unwell you are at the time.

About 1 in 5 people with diverticulitis develop complications. The people most at risk are those under 50.

About 15% of people with diverticular disease or diverticulitis have some bleeding. It's usually painless and quick, and in 70% to 80% of cases it stops by itself.

If the bleeding doesn't stop on its own, you may lose a lot of blood and need an emergency blood transfusion. If the bleeding is severe, you may have to be admitted to hospital so the doctors can monitor you.

When diverticulitis causes the inflamed part of the bowel to lie against the bladder, you may notice urinary problems. These can include:

• pain when urinating (dysuria)
• needing to urinate more often than usual
• in rare cases, air in the urine

The most common complication of diverticulitis is an abscess outside the large intestine (colon). An abscess is a pus-filled cavity or lump in the tissue. Doctors usually treat it with a technique called percutaneous abscess drainage (PAD).

A radiologist (a specialist in the use of imaging equipment, such as computerised tomography (CT) scans) uses an ultrasound or CT scanner to find where the abscess is.

A fine needle connected to a small tube is passed through the skin of your abdomen (stomach) and into the abscess. The tube is then used to drain the pus out. PAD is done under a local anaesthetic.

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

A fistula is another common complication of diverticulitis. It's an abnormal tunnel that connects 2 parts of the body, such as your intestine and your abdominal wall or bladder.

When infected tissues touch each other, they can stick together. Once the tissues have healed, a fistula may form. Fistulas can be serious, because they can let bacteria in your large intestine travel to other parts of your body and cause infections, such as an infection of the bladder (cystitis).

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

Rarely, an infected diverticulum (a small pouch in your colon) can split open. This is called perforation, and it lets the infection spread into the lining of your abdomen. An infection of that lining is known as peritonitis.

Peritonitis can be life-threatening, so you need treatment with antibiotics straight away. You may also need surgery to drain any pus that has built up, and sometimes the surgeon has to perform a colostomy.

If the infection has left bad scars on your large intestine, it can become partly or fully blocked. A fully blocked large intestine is a medical emergency, because the tissue of the bowel starts to decay and can eventually split, which leads to peritonitis.

A partly blocked large intestine is less urgent, but you still need treatment. Left alone, it will affect how well you digest food and cause you a good deal of pain.

Blockage from diverticular disease is very rare. Other causes, such as cancer, are more common, and this is one reason your doctor will look into your symptoms.

In some cases, the blocked part can be removed during surgery. But if the scarring and blockage are more extensive, you may need a colostomy, either temporary or permanent.

A high-fibre diet may help prevent diverticular disease, and it should improve your symptoms if you already have it.

Keep your diet balanced, with at least 5 portions of fruit and vegetables a day, plus whole grains. Adults should eat between 18g (0.6oz) and 30g (1.05oz) of fibre a day, depending on their height and weight. Your doctor can give you a more specific target based on your own height and weight.

It's recommended that you raise your fibre intake gradually, over a few weeks. This helps prevent the side effects of a high-fibre diet, such as bloating and flatulence (wind). Drinking plenty of fluids helps prevent them too.

If you have established diverticular disease, you may be advised to avoid nuts, corn and seeds, because they could block the diverticular openings and cause diverticulitis. People usually find out for themselves whether these foods cause symptoms. Probiotics have also been recommended, but there isn't good evidence for them. In general, good quality scientific evidence on how to prevent diverticular disease is lacking.

• fruit
• vegetables
• nuts
• breakfast cereals, but check the fibre content because some are very low
• starchy foods, such as brown bread, rice and pasta

Once you have reached your fibre target, stick to it for the rest of your life, if possible.

Good fresh fruit sources of fibre are listed below, with the amount of fibre in a typical portion:

• avocado pear: a medium-sized avocado pear contains 4.9g of fibre
• pear (with skin): a medium-sized pear contains 3.7g of fibre
• orange: a medium-sized orange contains 2.7g of fibre
• apple (with skin): a medium-sized apple contains 2g of fibre
• raspberries: 2 handfuls of raspberries (80g) contain 2g of fibre
• banana: a medium-sized banana contains 1.7g of fibre
• tomato juice: 1 small glass of tomato juice (200ml) contains 1.2g of fibre

Dried fruit can be a good source of fibre. Here is how much you get in a typical portion:

• apricots: 3 whole apricots contain 5g of fibre
• prunes: 3 whole prunes contain 4.6g of fibre

Good vegetable sources of fibre are listed below, with the amount of fibre in a typical portion.

• baked beans (in tomato sauce): half a can (200g) contains 7.4g of fibre
• red kidney beans (boiled): 3 tablespoons contain 5.4g of fibre
• peas (boiled): 3 heaped tablespoons contain 3.6g of fibre
• French beans (boiled): 4 heaped tablespoons contain 3.3g of fibre
• Brussel sprouts (boiled): 8 sprouts contain 2.5g of fibre
• potatoes (old, boiled): 1 medium-sized potato contains 2.4g of fibre
• spring greens (boiled): 4 heaped tablespoons contain 2.1g of fibre
• carrots (boiled, sliced): 3 heaped tablespoons contain 2g of fibre

Nuts are a good source of fibre, and these are some of the better ones, with the amount of fibre in a typical portion:

• almonds: 20 almonds contain 2.4g of fibre
• peanuts (plain): a tablespoon of peanuts contains 1.6g of fibre
• mixed nuts: a tablespoon of mixed nuts contains 1.5g of fibre
• Brazil nuts: 10 Brazil nuts contain 1.4g of fibre

These breakfast cereals are good sources of fibre, and the amount in a typical portion is given next to each one:

• All-Bran: a medium-sized bowl contains 9.8g of fibre
• Shredded Wheat: 2 pieces contain 4.3g of fibre
• Bran Flakes: 1 medium-sized bowl contains 3.9g of fibre
• Weetabix: 2 Weetabix contain 3.6g of fibre
• muesli (no added sugar): 1 medium-sized bowl contains 3.4g of fibre
• porridge (made with milk or water): 1 medium-sized bowl contains 2.3g of fibre

The 'own-brand' versions of these cereals should have similar levels of fibre.

Good sources of fibre in starchy food, along with the amount in typical portions, include:

• crispbread: 4 crispbreads contain 4.2g of fibre
• pitta bread (wholemeal): 1 piece (75g) contains 3.9g of fibre
• pasta (plain, fresh-cooked): 1 medium portion of pasta (200g) contains 3.8g of fibre
• wholemeal bread: 2 slices of wholemeal bread contain 3.5g of fibre
• naan bread: 1 piece of naan bread contains 3.2g of fibre
• brown bread: 2 slices of brown bread contain 2.5g of fibre
• brown rice (boiled): 1 medium portion of brown rice (200g) contains 1.6g of fibre

Fibre supplements are also available from pharmacists and health food shops. They usually come as sachets of powder that you mix with water. Some contain sweetener. A tablespoon of fibre supplement contains around 2.5g of fibre. If you need fibre supplements for the long term, your doctor can prescribe them.