Diverticular disease and diverticulitisSee all parts of this guide Hide guide parts
About diverticular disease and diverticulitis
Diverticular disease and diverticulitis are related digestive conditions that affect the large intestine (colon).
In diverticular disease, small bulges or pockets (diverticula) develop in the lining of the intestine. Diverticulitis is when these pockets become inflamed or infected.
Symptoms of diverticular disease include:
- lower abdominal pain
- feeling bloated
The majority of people with diverticula will not have any symptoms; this is known as diverticulosis.
Symptoms of diverticulitis tend to be more serious and include:
- more severe abdominal pain, especially on the left side
- high temperature (fever) of 38C (100.4F) or above
- diarrhoea or frequent bowel movements
Read more about the symptoms of diverticular disease and diverticulitis.
Diverticulosis, diverticular disease and diverticulitis
"Diverticula" is the medical term used to describe the small bulges that stick out of the side of the large intestine (colon).
Diverticula are common and associated with ageing. The large intestine becomes weaker with age, and the pressure of hard stools passing through the large intestine is thought to cause the bulges to form.
Read more about the causes of diverticula.
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.
1 in 4 people who develop diverticula will experience symptoms, such as abdominal pain.
Having symptoms associated with diverticula is known as diverticular disease.
Diverticulitis describes infection that occurs when bacteria becomes trapped inside one of the bulges, triggering more severe symptoms.
Diverticulitis can lead to complications, such as an abscess next to the intestine.
Read more about the complications of diverticulitis.
Treating diverticular disease and diverticulitis
A high-fibre diet can often ease symptoms of diverticular disease, and paracetamol can be used to relieve pain – other painkillers such as aspirin or ibuprofen are not recommended for regular use, as they can cause stomach upsets. Speak to your GP if paracetamol alone is not working.
Mild diverticulitis can usually be treated at home with antibiotics prescribed by your GP. More serious cases may need hospital treatment to prevent and treat complications.
Surgery to remove the affected section of the intestine is sometimes recommended if there have been serious complications, although this is rare.
Read more about treating diverticular disease and diverticulitis.
Who is affected
Diverticular disease is one of the most common digestive conditions.
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. Overall, symptoms of diverticulitis are most likely to occur in people over 70 years old.
Diverticular disease is often described as a "Western disease" because the rates are high in European and North American countries, and low in African and Asian countries.
A combination of genetics and diet is thought to be the reason for this and the fact that people in Western countries tend to eat less fibre.
People aged 50-70 who eat a high-fibre diet (25g a day) have a 40% lower chance of admission to hospital with complications of diverticular disease – compared to others in their age range with the lowest amount of dietary fibre.
Symptoms of diverticular disease and diverticulitis
Symptoms of diverticular disease and diverticulitis include abdominal pain, bloating and a change in normal bowel habits.
If diverticula have been discovered during a camera test for another reason (colonoscopy) or during a CT scan, you may be worried about what this means.
However, if you have never had abdominal pain or bouts of diarrhoea, there is a 70-80% 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. It's thought that a high-fibre diet is likely to reduce the risk of any symptoms developing.
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 and breaking wind (flatulence) may help relieve the pain.
Other long-term 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 – a classic pattern is multiple trips to the toilet in the morning to pass stools like "rabbit pellets"
Another possible symptom of diverticular disease is bleeding dark purple blood from your rectum (back passage). This usually occurs after diarrhoea-like cramping pain, and often leads to hospital admission, but fortunately this is an uncommon complication.
Diverticular disease does not cause weight loss, so if you are losing weight, seeing blood in your stools or experiencing frequent bowel changes, see your GP.
Diverticulitis shares most of the symptoms of diverticular disease (see above). However, the pain associated with diverticulitis is constant and severe, rather than intermittent. It is most likely to occur if you have previously had symptoms of diverticular disease, and develops 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, 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 East Asian people tend to develop diverticula in a different part of their colon for genetic reasons.
When to seek medical advice
Contact your GP as soon as possible if you think you have symptoms of diverticulitis.
If you have symptoms of diverticular disease and the condition has previously been diagnosed, you do not usually need to contact your GP as the symptoms can be treated at home.
Read more about the treatment of diverticular disease.
If you have not been diagnosed with the condition, contact your GP so they can rule out other conditions with similar symptoms, such as:
Irritable bowel syndrome (IBS) can also cause similar symptoms to diverticular disease.
Causes of diverticular disease and diverticulitis
Diverticular disease is caused by small bulges in the large intestine (diverticula) developing and becoming inflamed. If any of the diverticula become infected, this leads to symptoms of diverticulitis.
The exact reason why diverticula develop is not known, but they are associated with not eating enough fibre.
Fibre makes your stools softer and larger, so less pressure is needed by your large intestine to push them out of your body.
The pressure of moving hard, small pieces of stools through your large intestine creates weak spots in the outside layer of muscle. This allows the inner layer (mucosa) to squeeze through these weak spots, creating the diverticula.
There is currently no clinical evidence to fully prove the link between fibre and diverticula. However, diverticular disease and diverticulitis are both much more common in Western countries, where many people do not eat enough fibre.
It is not known why only 1 in 4 people with diverticula go on to have symptoms of diverticulitis. Diverticular disease may be chronic low-level diverticulitis. The symptoms are very similar to irritable bowel syndrome (IBS) and may overlap.
However, factors that appear to increase your risk of developing diverticular disease include:
- 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 developing diverticular disease is unclear.
Diverticulitis is caused by an infection of one or more of the diverticula.
It is thought an infection develops when a hard piece of stool or undigested food gets trapped in one of the pouches. This gives bacteria in the stool the chance to multiply and spread, triggering an infection.
Diagnosing diverticular disease and diverticulitis
Diverticular disease can be difficult to diagnose from the symptoms, alone because there are other conditions that cause similar symptoms, such as irritable bowel syndrome (IBS).
As a first step, your GP may recommend 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 is not a more serious cause of your symptoms, your GP may refer you for a colonoscopy, where a thin tube with a camera at the end (a colonoscope) is inserted into your rectum and guided into your colon. Before the procedure begins, you will be given a laxative to clear out your bowels.
A colonoscopy is not usually painful, but it can feel uncomfortable. You may be offered painkilling medication and a sedative beforehand to make you feel more relaxed and help reduce any discomfort.
CT pneumocolon or colonography
Another technique for confirming the presence of diverticula is a computerised tomography (CT scan). A CT scan uses X-rays and a computer to create detailed images of the inside of the body.
As with a colonoscopy, you will be given a laxative to clear out your bowels before you have the CT scan.
Unlike a regular CT scan, the colonography scan involves a tube being inserted into your rectum, which is used to pump some air up into your rectum. The CT scan is then taken with you lying on your front, and again lying on your back.
You may need to have an injection of contrast dye before the scan, but this is not always necessary.
If you have had a previous history of diverticular disease, your GP will usually be able to diagnose diverticulitis from your symptoms and a physical examination. A blood test may be taken, because a high number of white blood cells indicates infection. If your symptoms are mild, your GP will treat it at home and you should recover within 4 days.
Further tests will be needed if you have no previous history of diverticular disease.
If you are unwell, your GP may refer you to hospital for blood tests and investigations. This is to look for complications of diverticulitis and to rule out other possible conditions, such as gallstones or a hernia.
An ultrasound scan may be used, as well as a CT scan.
A CT scan may also be used if your symptoms are particularly severe. This is to check whether a complication, such as a perforation or an abscess, has occurred.
Treating diverticular disease and diverticulitis
Treatment options for diverticular disease and diverticulitis depend on how severe your symptoms are.
Most cases of diverticular disease can be treated at home.
The over-the-counter painkiller paracetamol is recommended to help relieve your symptoms.
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 your symptoms. Some people will notice an improvement after a few days, although it can take around a month to feel the benefits fully. Read more advice about using diet to improve the symptoms of diverticular disease.
If you have constipation, you may be given a bulk-forming laxative. These can cause flatulence (wind) and bloating. 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. 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 and may need a blood transfusion.
Signs that you may be experiencing heavy bleeding (aside from the amount of blood) include:
- feeling very dizzy
- mental confusion
- pale clammy skin
- shortness of breath
If you suspect that you (or someone in your care) is experiencing heavy bleeding, seek immediate medical advice. Contact your GP at once. If this is not possible then call NHS 24 111 service or your local out-of-hours service.
Treatment at home
Mild diverticulitis can often be treated at home. Your GP will prescribe antibiotics for the infection and you should take paracetamol for the pain. It's important that you finish the complete course of antibiotics, even if you are feeling better.
Some types of antibiotics used to treat diverticulitis can cause side effects in some people, including vomiting and diarrhoea.
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 can gradually introduce solid foods over the next 2 or 3 days.
For the 3 to 4 days of recovery, a low-fibre diet is suggested, until you return to the preventative high-fibre diet. This 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 GP may refer you for a test such as a colonoscopy or CT colonography after the symptoms have settled.
Treatment at hospital
If you have more severe diverticulitis, you may need to go to hospital, particularly 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 GP suspects complications
- your symptoms fail to improve after two days 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 directly connected to your vein). Most people start to improve within 2 to 3 days.
In the past, surgery was recommended as a preventative measure for people who had 2 episodes of diverticulitis as a precaution to prevent complications.
This is no longer the case, as studies have found that in most cases, risks of serious complications from surgery (estimated to be around 1 in 100) usually outweigh the benefits.
However, there are exceptions to this, such as:
- 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, discuss both benefits and 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 is when a hole (perforation) has developed in the bowel. This is uncommon, but causes very severe abdominal pain, which needs an emergency trip to hospital.
Surgery for diverticulitis involves removing the affected section of your large intestine. This is known as a colectomy. There are 2 ways this operation can be performed:
- an open colectomy – where the surgeon makes a large incision (cut) in your abdomen (stomach) and removes a section of your large intestine
- laparoscopic colectomy – a type of "keyhole surgery" where the surgeon makes a number of small incisions in your abdomen and uses special instruments guided by a camera to remove a section of large intestine
Open colectomies and laparoscopic colectomies are thought equally effective in treating diverticulitis, and have a similar risk of complications. People who have laparoscopic colectomies tend to recover faster and have less pain after the operation.
Emergency surgery when the bowel has perforated is more likely to be open and may result in a stoma being formed (see below).
Stoma surgery ('having a bag')
In some cases, the surgeon may decide your large intestine needs to heal before it can be reattached, or that too much of your large intestine has been removed to make reattachment possible.
In such cases, stoma surgery provides a way of removing waste materials from your body without using all of your large intestine. It is known as "having a bag" as a bag is stuck to the skin on your belly and the faeces (poo) are collected in the bag.
Stoma surgery involves the surgeon making a small hole in your abdomen – known as a stoma. There are 2 ways this procedure can be carried out:
- An ileostomy – where a stoma is made in 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 – where a stoma is made in your lower abdomen and a section of your large intestine 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 large intestine has recovered from the surgery. This will depend on the situation when you had the operation. If it was an emergency operation, you may need a few months to recover before having surgery to reverse the stoma.
If a large section of your large intestine is affected by diverticulitis and needs to be removed, or if you have multiple other conditions that make major surgery a risk, you may need a permanent ileostomy or colostomy.
Results of surgery
In general terms, elective (non-emergency) surgery is usually successful, although it does not achieve a complete cure in all cases. Following surgery, an estimated 1 in 12 people will have a recurrence of symptoms of diverticular disease and diverticulitis.
In an emergency setting, the success rate depends on how unwell you are when you require the operation.
Complications of diverticular disease and diverticulitis
Complications of diverticulitis affect 1 in 5 people with the condition. Those most at risk are aged under 50.
Some complications associated with diverticulitis are discussed below.
Around 15% of people with diverticular disease or diverticulitis experience bleeding, which is usually painless, quick and resolves itself in 70-80% of cases.
However, if the bleeding does not resolve itself, an emergency blood transfusion may be required due to excessive bleeding. If the bleeding is severe, you may need to be admitted to hospital for monitoring.
Diverticulitis can lead to the inflamed part of the bowel being in contact with the bladder. This may cause urinary problems, such as:
- 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. 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 (CT) scans) uses an ultrasound or CT scanner to locate the site of the abscess.
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 from the abscess. A PAD is performed under a local anaesthetic.
Depending on the size of the abscess, the procedure may need repeating several times before all the pus has been drained. If the abscess is very small – usually less than 4cm (1.5in) – it may be possible to treat it using antibiotics.
A fistula is another common complication of diverticulitis. Fistulas are abnormal tunnels that connect 2 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 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 the section of the colon that contains the fistula.
In rare cases, an infected diverticulum (pouch in your colon) can split, spreading the infection into the lining of your abdomen (perforation). 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 drain any pus that has built up, and it may be necessary to perform a colostomy.
If the infection has badly scarred your large intestine, it may become partially or totally blocked. A totally blocked large intestine is a medical emergency because the tissue of your large intestine will start to decay and eventually split, leading to peritonitis.
A partially blocked large intestine is not as urgent, but treatment is still needed. If left untreated, it will affect your ability to digest food and cause you considerable pain.
Intestinal blockage from diverticular disease is very rare. Other causes, such as cancer, are more common. This is one of the reasons your GP will investigate your symptoms.
In some cases, the blocked part can be removed during surgery.
However, if the scarring and blockage is more extensive, a temporary or permanent colostomy may be needed.
Preventing diverticular disease and diverticulitis
Eating a high-fibre diet may help prevent diverticular disease, and should improve your symptoms.
Your diet should be balanced and include at least 5 portions of fruit and vegetables a day, plus whole grains. Adults should aim to eat 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's recommended that you gradually increase your fibre intake over the course of a few weeks. This will help prevent side effects associated with a high-fibre diet, such as bloating and flatulence (wind). Drinking plenty of fluids will also help prevent side effects.
If you have established diverticular disease, it may be suggested that you avoid eating nuts, corn and seeds due to the possibility that they could block the diverticular openings and cause diverticulitis. People usually find out themselves if these foods cause symptoms. Probiotics have also been recommended, but evidence is lacking. Overall, there is a lack of good quality scientific evidence on how to prevent diverticular disease.
Sources of fibre
Good sources of fibre include
- breakfast cereals – but check fibre content as 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.
More detailed information on sources of fibre is provided below.
Good sources of fibre in fresh fruit (plus the amount of fibre that is found in typical portions) include:
- 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
Good sources of fibre in dried fruit (plus the amount of fibre found in typical portions) include:
- apricots – 3 whole apricots contain 5g of fibre
- prunes – 3 whole prunes contain 4.6g of fibre
Good sources of fibre in vegetables (plus the amount of fibre found in typical portions) include:
- baked beans (in tomato sauce) – a half can of baked beans (200g) contains 7.4g of fibre
- red kidney beans (boiled) – 3 tablespoons of red kidney beans contain 5.4g of fibre
- peas (boiled) – 3 heaped tablespoons of peas contain 3.6g of fibre
- French beans (boiled) – 4 heaped tablespoons of French beans contain 3.3g of fibre
- Brussel sprouts (boiled) – 8 Brussel sprouts contain 2.5g of fibre
- potatoes (old, boiled) – 1 medium-sized potato contains 2.4g of fibre
- spring greens (boiled) – 4 heaped tablespoons of Spring greens contain 2.1g of fibre
- carrots (boiled, sliced) – 3 heaped tablespoons of carrots contain 2g of fibre
Good sources of fibre in nuts (plus the amount of fibre found in typical portions) include:
- 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
Good sources of fibre in breakfast cereals (plus the amount of fibre found in typical portions) include:
- All-Bran – a medium-sized bowl of All-Bran contains 9.8g of fibre
- Shredded Wheat – 2 pieces of Shredded wheat contain 4.3g of fibre
- Bran Flakes – 1 medium-sized bowl of Bran flakes contains 3.9g of fibre
- Weetabix – 2 Weetabix contain 3.6g of fibre
- muesli (no added sugar) – 1 medium-sized bowl of muesli contains 3.4g of fibre
- porridge (milk or water) – 1 medium-sized bowl of porridge contains 2.3g of fibre
Note – the "own-brand" equivalents of the cereals mentioned above should contain similar levels of fibre.
Good sources of fibre in starchy food (plus the amount found 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 – usually in the form of sachets of powder you mix with water – are also available from pharmacists and health food shops. Some contain sweetener. A tablespoon of fibre supplement contains around 2.5g of fibre. If you require long-term fibre supplements, your GP can prescribe them.
14 February 2020
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