Diverticula of the colon are common in older people. They commonly cause no symptoms, and in most cases no treatment is needed. However, a high-fibre diet is usually advised to help prevent complications. In some cases, diverticula cause pain and other symptoms. Sometimes a diverticulum may bleed and cause a sudden, painless bleed from the back passage (anus), which can be heavy. In some cases, one or more diverticula become infected to cause diverticulitis. This can cause severe tummy (abdominal) pain and high temperature (fever). A course of medicines called antibiotics may be required. Complications caused by diverticulitis - such as a collection of pus (abscess) or a perforated bowel - are uncommon, but are serious.
What are diverticula?
Diverticula is the medical term to describe small bulges that stick out of the colon wall. A diverticulum (singular) is a small pouch with a narrow neck that sticks out from (protrudes from) the wall of the gut (intestine). 'Diverticula' means more than one diverticulum. They can develop on any part of the gut but usually occur in the colon (sometimes called the large bowel or large intestine).
They most commonly develop in the section of the colon leading towards the back passage (rectum). This is where the stools (faeces) are becoming more solid. This is on the left-hand side of the tummy (abdomen). Several diverticula may develop over time. Some people eventually develop many diverticula.
How common are diverticula?
Diverticula are common. They become more common with increasing age. About half of all people in the UK have diverticula by the time they are 50 years old. Nearly 7 in 10 have diverticula by the time they are 80 years old.
What causes diverticula?
The reason why diverticula develop is probably related to not eating enough fibre. Fibre is the part of food that is not digested but helps the digestive system to produce healthy soft stools.
The gut (intestine) moves stools (faeces) along with gentle squeezes of its muscular wall. The stools tend to be drier, smaller, and more difficult to move along if there is insufficient fibre in the diet. The gut muscles have to work harder if there is too little fibre in the diet.
High pressure may develop in parts of the gut when it squeezes hard stools. The increased pressure may push the inner lining of a small area of the gut through the muscle wall to form a small diverticulum.
Symptoms of diverticula
It is common for there to be no symptoms - called diverticulosis
In about 3 in 4 people who develop diverticula, the diverticula cause no harm or symptoms. The term diverticulosis means that diverticula are present, but do not cause any symptoms or problems. In most cases, the condition will not be known about as there are no symptoms.
Sometimes diverticula are discovered as an incidental finding during tests such as a colonoscopy or barium enema for other reasons.
This term is used when diverticula cause intermittent, lower tummy (abdominal) pain or bloating (without swelling (inflammation) or infection - discussed later). The pain is usually crampy and tends to come and go. The pain is most commonly in the lower left part of the tummy (abdomen).
The pain and bloating may reduce after going to the toilet to pass stools (faeces). Some people develop diarrhoea or constipation, and some people pass mucus with their stools. It is not clear how diverticula cause these symptoms.
Symptoms of diverticular disease can be similar to those that occur with a condition called irritable bowel syndrome (IBS). However, IBS usually affects younger adults. So, symptoms that first develop in a younger adult are more likely to be due to IBS and symptoms that first develop in older people are more likely to be due to diverticular disease. However, in some cases it is difficult to tell if symptoms are due to diverticular disease or to IBS.
Diverticulitis is a condition where one or more of the diverticula become inflamed and infected. This may occur if some faeces get trapped and stagnate in a diverticulum. Germs (bacteria) in the trapped faeces may then multiply and cause infection.
About 1 in 5 people with diverticula develop a bout of diverticulitis at some stage. Some people have recurring bouts of diverticulitis. Symptoms of diverticulitis include:
- A constant pain in the abdomen. It is most commonly in the lower left side of the abdomen, but can occur in any part of the abdomen.
- High temperature (fever).
- Constipation or diarrhoea.
- Some blood mixed with the stools.
- Feeling sick (nauseated) or being sick (vomiting).
- Tenderness over the abdomen when being examined.
Complications of diverticula, diverticula disease and diverticulitis
Obstruction, abscess, fistula, and peritonitis
An infected diverticulum (diverticulitis) sometimes gets worse and causes complications. Possible complications include:
- A blockage (obstruction) of the colon.
- A collection of pus (abscess) that may form in the abdomen.
- A channel (fistula) that may form to other organs such as the bladder.
- A hole (perforation) in the wall of the bowel that can lead to infection inside the abdomen (peritonitis).
Surgery is usually needed to treat these serious but uncommon complications.
A diverticulum may occasionally bleed and some blood may be passed via the back passage (anus). The bleeding is usually abrupt and painless. The bleeding is due to a burst blood vessel that sometimes occurs in the wall of a diverticulum and so the amount of blood loss can be heavy.
A very large bleed requiring an emergency blood transfusion occurs in some cases. However, the bleeding stops on its own in about three in four cases. Sometimes an operation is needed to stop the bleeding. Sometimes just a slight bleed occurs.
Note: always report bleeding from the bowel (via the anus) to a doctor. It should never be assumed that bleeding is from a diverticulum. Other more serious conditions such as bowel cancer need to be ruled out.
Diagnosing diverticula, diverticula disease and diverticulitis
A diagnosis of presumed diverticular disease can be made by taking a history and examination. A definite diagnosis of diverticular disease would be made by confirming the presence of diverticula and ruling out other causes of the symptoms during tests such as colonoscopies.
But: the symptoms of diverticular disease, especially if they start in an older person, can also be similar to those of early bowel cancer.
A test called colonoscopy may be advised. To carry out this test, a doctor uses a special flexible telescope to look into the bowel. This can confirm the presence of diverticula, and rule out bowel cancer. CT scans can also help, particularly in people who are unable to tolerate a colonoscopy.
However a colonoscopy or scan is not always needed if the symptoms seem obvious.
Treatment for diverticula (diverticulosis)
As diverticulosis means diverticula with no symptoms, there is no need for any treatment.
However, a high-fibre diet is usually advised for people with diverticulosis. A high-fibre diet is generally considered a good thing for everyone - whether they have diverticula or not. Adults should aim to eat between 18 and 30 grams of fibre per day.
Fibre helps to make larger and softer stools (faeces) and helps to prevent constipation. Also, a high-fibre diet may prevent further diverticula from forming. This may reduce the risk of developing problems in the future with diverticula, such as diverticulitis. See the next section for more details of a high-fibre diet.
There is evidence that you may reduce your risk of developing symptoms if you:
Treatment for diverticular disease
A high-fibre diet is usually advised as it helps to keep stools (faeces) soft and bulky and reduces pressure on the colon. It can ease pain, bloating, constipation and diarrhoea and prevents hard stools becoming lodged within the pouches. It can also help to prevent the formation of further diverticula, which may reduce the risk of the condition getting any worse.
We need about 18 g of fibre each day, which should come from a variety of high-fibre foods. Symptoms of wind and bloating may develop if suddenly increasing the amount of fibre eaten. Any increase should be gradual to prevent this, and to allow the gut (intestine) to become used to the extra fibre.
A useful guide is to make one change every few days, for example, starting by swapping white bread for wholemeal bread. It is helpful to introduce something new every few days, such as adding beans or extra vegetables to a casserole or Bolognese, or having a piece of fruit for pudding.
High-fibre foods to include:
- Whole grains, fruit and vegetables.
- Wholemeal or wholewheat bread and flour (for baking).
- Wholegrain breakfast cereals such as All-Bran®, Weetabix®, muesli, etc.
- Brown rice and wholewheat pasta.
- Wheat bran.
- Beans, pulses and legumes.
Meeting the government recommendation of eating at least five fruit and vegetable portions each day will help to get plenty of fibre. A portion is about 80 g or what roughly fits in the palm of a hand. Apples, pears, oranges, blueberries, strawberries, broccoli, asparagus and dried figs are all excellent fibre sources.
Fibre supplements or a bulk-forming laxative may be advised if a high-fibre diet does not ease symptoms. Several types are available at pharmacies, health food shops, or on prescription. Although the effects of fibre supplements to ease symptoms may be seen in a few days, it may take as long as four weeks.
Note: some people have a different response to fibre than others. So it is very much trial and error as to what is most suitable for each individual. Some people report that a high-fibre diet or certain fibre supplements cause some persistent mild symptoms such as mild pains and bloating. This may be to do with the type of fibre being consumed.
Insoluble fibre, found in cereals, wheat bran and nuts, may cause more wind and bloating. Eating a lot of bran-based foods or taking bran supplements can particularly aggravate symptoms in some people. Therefore, it may be helpful to have more soluble fibre (the type of fibre that can be dissolved in water), found mostly in fruit and vegetables.
However, many foods contain both types of fibre, so when introducing a new high-fibre food, monitor your symptoms and adjust the diet accordingly.
- Dietary sources of soluble fibre include oats, ispaghula (psyllium), nuts, flax seeds, lentils, beans, fruit and vegetables. A fibre supplement called ispaghula powder is also available from pharmacies and health food shops.
- Insoluble fibre is chiefly found in corn (maize) bran, wheat bran, nuts and some fruit and vegetables.
It is important to drink plenty of fluids when having a high-fibre diet or fibre supplements. The aim should be to drink at least two litres (about 8-10 cups) per day. Fluid intake should be mainly from water, but tea, coffee and herbal teas all contribute.
Fizzy drinks and juice drinks contain a lot of sugar so try to limit these. One 150 ml glass of fruit juice each day only counts as a portion of fruit. It is important to choose varieties that are 100% fruit juice and do not contain added sugar.
Paracetamol can ease pain if a high-fibre diet or fibre supplements do not help so much to ease pain. Other types of painkiller are not usually used for diverticular disease. Anti-inflammatory drugs (NSAIDs) and opioid medicines should particularly be avoided as these can cause perforation.
Treatment for diverticulitis
When symptoms are not too severe
Diverticulitis often requires a course of antibiotic medicine , particularly if feeling generally unwell. The diverticulosis diet recommendations should be followed unless otherwise advised. Painkillers may be needed alongside the antibiotics. If the infection is not too severe then symptoms may well settle with this treatment.
Diverticulitis - when to go to hospital
If symptoms are severe or prolonged then admission to hospital may be needed. Fluids may be given directly into a vein via a drip (intravenous fluids). Antibiotics may be required, either in tablet form or intravenously.
Painkilling injections might also be used. Admission to hospital might also be considered if the symptoms are not too severe but are not settling after a couple of days of treatment at home.
If complications develop
As mentioned earlier, some people with diverticulitis develop complications such as:
- Bowel blockage (obstruction).
- A collection of pus (an abscess).
- A channel (fistula) that may form to other organs.
- A tummy (abdominal) infection (peritonitis).
Surgery is usually needed to treat these serious but uncommon complications. For example, surgery is sometimes needed to drain an abscess or to remove a badly infected part of the colon.
Treatment of bleeding diverticula
As mentioned earlier, a large bleed requiring an emergency blood transfusion sometimes occurs in people with diverticula. However, the bleeding stops on its own in about 3 in 4 cases. Sometimes an operation is needed to stop the bleeding.
When to see a doctor
It is always important to seek medical advice if there is a change in the pattern of your toilet habit. For example, this can include a sudden change from your normal bowel habit to persisting constipation or diarrhoea, passing blood or mucus, or new pains.
Even if known to have diverticula, a change of symptoms may indicate a new and different gut (intestinal) problem.
Further reading and references
Diverticular disease: diagnosis and management; NICE Guidance (November 2019)
FejlehM et al; Colonoscopic management of diverticular disease, World J Gastrointest Endosc. 202012(2):53–59.
Strate LL, Morris AM; Epidemiology, Pathophysiology, and Treatment of Diverticulitis. Gastroenterology. 2019 Apr156(5):1282-1298.e1. doi: 10.1053/j.gastro.2018.12.033. Epub 2019 Jan 17.
Diverticular disease; NICE CKS, May 2023 (UK access only)