Diverticulosis, Diverticulitis and Diverticular Bleeding

What is a diverticulum?

Over time, small pouches may form in the wall of the large bowel, pushing outwards. Each of these small pouches is called a diverticulum, and having more than one is called diverticulosis.

Diverticula are seen most often in the last parts of the large bowel, particularly in the sigmoid colon. They become more common as age advances.

Having diverticula does not by itself mean having a disease. In most people diverticula cause no complaint at all and are noticed by chance during a colonoscopy or imaging done for some other reason.

Are diverticulosis and diverticulitis the same thing?

No. This distinction is very important.

Diverticulosis: the presence of diverticula in the large bowel. There is no inflammation.

Diverticular disease: a broader concept, in which the diverticula give rise to pain, a change in bowel habit, bleeding or other problems.

Diverticulitis: the development of acute inflammation around one or more diverticula.

So “diverticula were seen” on a colonoscopy report does not mean the person has had diverticulitis.

Why do diverticula form?

There is no single cause.

Many factors are thought to play a part together: the changes that appear in the bowel wall with age, genetic susceptibility, the movements of the bowel, diet and lifestyle.

Diverticula used to be thought to form only as a result of “raised pressure inside the bowel because of constipation and a low intake of fibre”. Today the mechanism is known to be more complicated than that.

Genetic factors are important too. Certain lifestyle factors — obesity, physical inactivity, smoking, and a diet rich in red meat and poor in fibre — are associated with an increased risk of diverticulitis.

How common is diverticulosis?

It is very common, and its frequency increases markedly with age.

In United States data, for instance, diverticulosis is reported in more than 30% of adults between 50 and 59, and in more than 70% of those over 80. It should be remembered that these proportions can vary between countries and populations.

Against that, only a small proportion of people who have diverticula go on to develop diverticulitis. Current data show this proportion to be lower than was once thought.

Does diverticulosis cause symptoms?

Most of the time it causes no symptoms at all.

In some people there may be:

• Discomfort or pain in the lower abdomen,
• Bloating,
• Constipation,
• Diarrhoea or a change in bowel habit.

But these symptoms are also very common in other conditions, such as irritable bowel syndrome.

For this reason it is not always correct to say “I have diverticula, and that is the cause of all my abdominal complaints”.

What happens when diverticulitis develops?

When acute inflammation develops around a diverticulum, this is called diverticulitis.

The most typical symptom, particularly in Western populations, is pain that begins in the left lower abdomen and continues.

It may be accompanied by:

• Fever,
• Tenderness of the abdomen,
• Nausea or vomiting,
• Constipation,
• Sometimes diarrhoea.

The pain may begin suddenly, or may build up gradually over a few days.

Why does diverticulitis matter?

Most cases of diverticulitis are uncomplicated diverticulitis, with inflammation confined to the area around the bowel.

In some patients, complications such as these may develop:

Abscess: a collection of infected material around the bowel.

Perforation: a hole in the wall of the bowel.

Peritonitis: severe inflammation of the lining of the abdomen when bowel contents spread into the abdominal cavity.

Fistula: an abnormal connection forming between the bowel and another organ.

Stricture: narrowing of the bowel channel as a result of repeated inflammation and scarring.

Can a diverticulum form a fistula to the bladder?

Yes.

In sigmoid diverticulitis in particular, a colovesical fistula may develop between the bowel and the bladder.

These patients may have repeated urinary infections, air passing when they pass water or, less often, material resembling stool in the urine.

This is one of the complications of diverticulitis that calls for surgical assessment.

What is diverticular bleeding?

Diverticula can also cause bleeding without becoming inflamed.

Diverticular bleeding is mostly painless, and may appear as:

bright red or maroon blood from the back passage, sometimes in quite large amounts.

Some of these bleeds stop on their own. But larger bleeds in particular need assessment in hospital.

If the bleeding continues, the bleeding point can be found at colonoscopy and treated endoscopically. In some situations angiography and embolisation, and less often surgery, may be needed.

How is diverticulitis diagnosed?

The patient’s history and examination matter. Markers of inflammation such as the white cell count and CRP may be raised on blood tests.

But the symptoms alone are not always enough.

Computed tomography (CT)

Where acute diverticulitis is suspected, CT of the abdomen is one of the most important methods both for confirming the diagnosis and for looking for complications.

CT can assess:

• Diverticulitis,
• Inflammation around the bowel,
• Abscess,
• Perforation,
• Stricture.

CT is particularly important in people with no previous imaging-confirmed history of diverticulitis, or where severe or complicated disease is suspected.

Is a colonoscopy done during acute diverticulitis?

Generally, a routine colonoscopy is not done in the acute phase.

Once the active inflammation has settled, whether a colonoscopy is needed is assessed according to the patient’s age, their previous colonoscopy, the CT findings and whether the disease was complicated.

Colonoscopic assessment after recovery is important particularly in patients who have had complicated diverticulitis and who have not had a good-quality colonoscopy recently. The ACP likewise supports recommending colonoscopy after a first episode of complicated left-sided diverticulitis in patients who have not had one recently.

Where a colonoscopy is needed, it is generally done after the acute symptoms have settled completely.

Does every patient with diverticulitis need an antibiotic?

No.

This is one of the most important changes of recent years in the treatment of diverticulitis.

In the past, almost everyone diagnosed with acute diverticulitis was given an antibiotic.

Today, in selected patients whose immune system is normal, whose general condition is good and who have mild, uncomplicated diverticulitis, an antibiotic may not routinely be needed. The AGA recommends the selective use of antibiotics in this group.

But an antibiotic is needed in patients with:

• Complicated diverticulitis,
• An abscess,
• Signs of systemic infection,
• A suppressed immune system,
• Poor general condition,
• Certain high-risk features.

So neither “antibiotics are not used in diverticulitis” nor “every diverticulitis definitely needs an antibiotic” is correct.

Is admission to hospital needed?

Not every patient needs to be admitted.

Some patients with mild, uncomplicated diverticulitis who can take fluids and have no important risk factors can be treated at home under a doctor’s supervision.

Hospital treatment may be needed for people with severe pain, high fever, an inability to take fluids because of vomiting, serious accompanying illness, a suppressed immune system, or a complication.

What is done if an abscess develops?

Small abscesses can be brought under control with antibiotic treatment in some patients.

For larger abscesses, or those that do not respond to treatment, percutaneous drainage through the skin under imaging guidance can be used.

In some patients surgical treatment is then considered.

Is an operation needed in diverticulitis?

In most patients it is not.

Emergency surgery may be needed particularly for uncontrolled perforation, widespread peritonitis, or serious complications that cannot be brought under control with medical treatment.

Planned surgery, on the other hand, is assessed individually in recurrent or complicated disease.

There is an important recent change here:

The fixed rule “if you have had diverticulitis three times you must have an operation” is no longer accepted.

The decision to operate should be made not on the number of attacks alone, but taking into account their severity, any complications, the presence of a fistula or a stricture, the patient’s quality of life, their other illnesses and their preferences.

How should I eat with diverticular disease?

An acute attack of diverticulitis and long-term eating need to be separated from one another.

During an acute attack

In some patients a short period of clear fluids or a mainly liquid diet may bring relief. As the complaints begin to settle, a gradual return to normal eating follows.

Staying on fluids alone unnecessarily for a long time is not right.

Between attacks

In the long term, a good diet rich in plant foods and natural sources of fibre is preferred.

Vegetables, fruit, wholegrains and pulses are part of healthy eating in suitable people.

Are seeds, nuts and dried fruit forbidden?

No.

This is one of the commonest old beliefs about diverticular disease.

In the past, in the belief that small fragments could enter the diverticula and cause diverticulitis, patients were advised to stay away from seeds, hazelnuts, walnuts, sweetcorn and similar foods.

Today there is no approach that requires these foods to be forbidden routinely.

If a person notices a particular food that troubles them, an individual adjustment can of course be made; but there is no need to forbid all seeds and nuts simply because diverticula are present.

What can be done to avoid another episode of diverticulitis?

There is no method that prevents recurrence completely.

Even so, a healthy way of living can help reduce the risk:

• Eating well and with plenty of fibre,
• Not eating red meat to excess,
• Regular physical activity,
• Keeping to a healthy body weight,
• Not smoking,
• Avoiding unnecessary and frequent use of NSAID-type painkillers.

The AGA regards these lifestyle measures as important parts of the approach to reducing the risk of recurrence after diverticulitis.

Do probiotics, rifaximin or mesalazine prevent recurrence?

There are a great many different recommendations that patients may come across on the internet about this.

But the current AGA approach does not recommend the routine use of mesalazine, probiotics or rifaximin in patients who have had diverticulitis for the sole purpose of preventing further attacks.

The ACP likewise strongly recommends that mesalazine not be used to prevent recurrent diverticulitis.

The use of these drugs in other clinical situations has to be assessed separately.

Does diverticular disease turn into cancer?

Diverticula are not precursors of cancer, and diverticulosis does not turn directly into bowel cancer.

But acute diverticulitis and bowel cancer can sometimes produce similar symptoms and similar imaging findings.

For this reason the colon may need to be assessed properly once the acute phase has passed, particularly after complicated diverticulitis or in patients with suspicious findings.

This does not mean that “the diverticulitis has turned into cancer”; it is so that a cancer is not missed at the outset.

What is the outlook?

Most people who have diverticulosis have no serious trouble from it in their lifetime.

A substantial proportion of patients who do develop diverticulitis recover completely with appropriate treatment.

In some people the disease may recur. But the idea that each recurrence will be more dangerous than the last is not correct. According to AGA data, complicated diverticulitis most often appears at the first attack of the disease, and the risk of complications does not necessarily rise with repeated attacks.

When is emergency assessment needed?

In a person with diverticular disease, medical assessment is needed without delay if there is:

• Severe or increasing abdominal pain,
• High fever,
• Persistent vomiting,
• Marked swelling of the abdomen,
• An inability to pass wind or stool,
• Heavy bleeding from the back passage,
• Fainting, dizziness or serious weakness.

These may be signs of complications such as an abscess, obstruction of the bowel, perforation or significant bleeding.

Currency: The AGA’s current clinical approach to the management of diverticulitis, the recommendations of the American College of Physicians (ACP) and the NIH/NIDDK information on diverticular disease were taken into account in preparing this information.

This content is for general information. Treatment of diverticulitis should be planned according to the severity of the illness, whether complications are present, and the person’s other health characteristics.