Diverticular Disease and Diverticulitis

Diverticula are small sacs or pockets that form outwards in the wall of the large bowel. The presence of several diverticula in the bowel is called diverticulosis. Inflammation of the diverticula or infection of the surrounding tissues is called diverticulitis.

Although these terms are related, they do not mean the same thing:

• Diverticulosis: The presence of diverticula in the bowel. In most people it causes no symptoms.
• Diverticular disease: The occurrence of complaints such as abdominal pain, bloating, a change in bowel habit or bleeding due to diverticula.
• Diverticulitis: Inflammation of one or more of the diverticula.
• Diverticular bleeding: Usually painless, sudden bleeding from the anus resulting from bleeding of a blood vessel around a diverticulum.

Diverticulosis becomes more common with age. However, most people with diverticula never develop diverticulitis during their lifetime. Diverticula seen by chance during a colonoscopy do not mean cancer and do not on their own require surgery [1–4].

Most cases of diverticulitis follow an uncomplicated course. However, in some patients an abscess, perforation of the bowel, narrowing, obstruction or a fistula, meaning an abnormal connection with neighbouring organs, may develop. Treatment is planned individually according to the severity of the disease and whether there are complications.

Does diverticulosis cause symptoms?

Most people who have diverticula have no complaints at all. In some people, however:

• Recurrent pain or discomfort, especially in the lower left part of the abdomen
• Bloating and wind
• Constipation or diarrhoea
• Abdominal pain that eases after opening the bowels
• A change in bowel habit may occur.

These complaints are not specific to diverticular disease. Irritable bowel syndrome, inflammatory bowel conditions and, less commonly, tumours of the large bowel can also cause similar symptoms. For this reason, complaints that are new or long-lasting in particular should be assessed.

What symptoms does diverticulitis cause?

The most common symptom of acute diverticulitis is constant pain, usually felt in the lower left part of the abdomen. In Turkey and in Western populations, the disease most often occurs in the part of the bowel on the left side called the sigmoid colon. With right-sided diverticula, the pain may be in the lower right abdomen and may be confused with appendicitis.

The pain may be accompanied by the following symptoms:

• Fever and chills
• Nausea or vomiting
• Loss of appetite
• Constipation or diarrhoea
• Tenderness and bloating of the abdomen
• Burning when passing urine or passing urine frequently

Pain that becomes increasingly severe, rigidity of the abdomen, high fever, persistent vomiting, being unable to pass wind or stool, or a deterioration in general condition may suggest complicated diverticulitis and require urgent assessment.

How is diverticular bleeding recognised?

Diverticular bleeding usually appears as maroon or bright red bleeding from the anus that starts without pain. The bleeding can sometimes be heavy. It cannot be said with certainty that the blood comes from a diverticulum just by looking at the appearance of the stool.

If there is heavy bleeding, dizziness, palpitations, a feeling of faintness, low blood pressure or marked weakness, you should go to the emergency department.

Why do diverticula form?

Changes in the bowel wall that occur with age, genetic predisposition, bowel movements and lifestyle all play a part in the development of diverticula. Factors that may increase the risk of diverticular disease are:

• A diet low in fibre and high in red meat
• Excess weight
• An inactive lifestyle
• Smoking
• Regular or frequent use of non-steroidal painkillers
• Diseases or medicines that suppress the immune system
• Diverticular disease in the family

Regular use of non-steroidal anti-inflammatory drugs such as ibuprofen, naproxen and diclofenac may increase the risk of diverticulitis and diverticular bleeding. However, aspirin recommended by a doctor for cardiovascular disease should not be stopped without consulting your doctor [2].

How is diverticulosis detected?

Diverticula are often seen by chance during a colonoscopy, computed tomography or bowel imaging performed for another reason. In diverticulosis that causes no symptoms, further tests or treatment are not always necessary.

How is acute diverticulitis diagnosed?

The symptoms of diverticulitis can be confused with different conditions such as appendicitis, bowel infection, kidney stones, urinary tract infection, ovarian conditions and cancer of the large bowel. For this reason, it is not always possible to make a definite diagnosis based on symptoms alone.

The following tests may be used in the assessment:

• Blood tests: Markers of inflammation such as white blood cells and CRP are assessed.
• Urine test: Helps to distinguish causes such as urinary tract infection or kidney stones.
• Pregnancy test: May be necessary in patients who could be pregnant.
• Computed tomography (CT): The imaging method most commonly used to diagnose diverticulitis and determine the severity of the disease.

CT can show whether the inflammation is confined to the area around the bowel, and whether an abscess, free air, a fistula or an obstruction has developed. In selected patients who have had similar attacks previously confirmed by imaging, a new CT may not be needed for every attack. This decision is made by the doctor [1–4].

Is a colonoscopy performed during a diverticulitis attack?

A routine colonoscopy is generally not performed during the acute, painful phase. The procedure can be more difficult in an inflamed bowel and the risk of perforation may increase. If a colonoscopy is needed, it is usually planned after the symptoms have completely resolved, generally about 6–8 weeks later [2,3].

The decision on colonoscopy is personalised according to:

• Whether the attack was complicated
• Whether a good-quality, complete colonoscopy has been performed before
• The patient’s age and bowel cancer screening status
• The presence of warning symptoms such as anaemia, weight loss, blood in the stool or a change in bowel habit

A colonoscopy after the attack is particularly important in patients who have had complicated diverticulitis and have not had a recent good-quality colonoscopy. After an uncomplicated attack confirmed by CT, the need for colonoscopy is determined according to the person’s previous tests and screening status [2,3].

Treatment is planned according to whether the disease is uncomplicated or complicated, the patient’s general condition, the immune system, whether they can take enough fluids and whether they can be followed safely at home.

How is uncomplicated diverticulitis treated?

Many patients who are in good general condition, whose pain can be controlled, who can take fluids by mouth and in whom no abscess or perforation is found on CT can be treated without being admitted to hospital [2,3].

Treatment may include:

• Pain control
• Adequate fluid intake
• Temporary adjustment of diet according to symptoms
• Close follow-up by a doctor
• Antibiotics if necessary

During the acute phase, some patients may feel more comfortable with fluids or easily digestible foods. As the complaints ease, a normal diet is gradually resumed. Not every patient needs to take only fluids for a long time.

Does every patient with diverticulitis need antibiotics?

No. Current guidelines state that antibiotics may not need to be used routinely in selected patients with a normal immune system, good general condition and mild uncomplicated diverticulitis [2–4].

The decision to monitor without antibiotics should only be made after assessment by a doctor. Antibiotic treatment is more strongly considered in the following situations:

• A suppressed immune system
• Other illnesses together with advanced age, or general frailty
• High fever or marked signs of inflammation
• Persistent vomiting or inability to take fluids by mouth
• Severe or increasing complaints
• Widespread inflammation, fluid collection or suspected complications on CT
• Symptoms not improving or getting worse
• The presence of an abscess, perforation or other complications

Unnecessary use of antibiotics can lead to problems such as diarrhoea, allergy, changes in the gut microbiota and antibiotic resistance. On the other hand, not using them when they are needed can increase the risk of serious infection. For this reason, the decision should be made individually.

Which patients need to be admitted to hospital?

Hospital treatment may be needed in the following situations:

• Severe or uncontrollable pain
• High fever or deterioration in general condition
• Persistent vomiting and inability to take fluids
• An abscess, perforation, obstruction or widespread infection inside the abdomen
• A suppressed immune system
• Serious other illnesses
• No possibility of safe follow-up at home
• No improvement despite outpatient treatment

In hospital, fluids through a drip, pain treatment and, if necessary, antibiotics are given. The patient’s examination, blood results and imaging findings are monitored.

How is a diverticular abscess treated?

Small, contained abscesses may heal with antibiotic treatment in some patients. For larger abscesses or those that do not respond to treatment, it may be necessary to drain the abscess by placing a catheter through the skin under radiological guidance. This procedure is called percutaneous drainage.

Surgery may be needed if the abscess cannot be drained, the infection cannot be brought under control or the patient’s general condition worsens. Treatment is determined according to the size and location of the abscess and the patient’s clinical condition [1].

When does diverticulitis require emergency surgery?

Emergency surgical treatment may be considered in the following situations:

• Widespread inflammation of the lining of the abdomen (peritonitis) due to perforation of the bowel
• Infection inside the abdomen that cannot be brought under control
• An abscess that is not suitable for drainage or does not respond to treatment
• Bowel obstruction
• Uncontrollable bleeding
• Rapid deterioration in the patient’s general condition

During the operation, the diseased section of bowel, usually the sigmoid colon, is removed. In suitable patients, the two ends of the bowel can be joined in the same operation. However, in the case of widespread infection, a severe general condition of the patient or a join that is not considered safe, a temporary or, less commonly, permanent stoma may be needed.

The need for a stoma is not the same in every patient. The decision is made during the operation according to the extent of the infection, the condition of the bowel tissue and the patient’s general health.

In which situations is planned surgery considered?

The decision on planned surgery for diverticulitis is no longer made only according to the number of attacks a patient has had. The old approach of “surgery is always needed after two attacks” is not supported by current guidelines [1–4].

Planned sigmoid colon surgery may be considered in the following situations:

• Development of a fistula between the bowel and the bladder, vagina, skin or another organ
• Narrowing or obstruction of the bowel due to diverticulitis
• Recurrent or persistent complaints that markedly impair quality of life
• A high individual risk after a complicated attack such as an abscess
• Cancer that cannot be completely ruled out
• Particular risks in patients with a suppressed immune system
• Ongoing pain and bowel problems despite treatment

When the decision on surgery is made, the frequency and severity of attacks, the need for hospital admission, quality of life, surgical risk and the patient’s preferences are assessed together.

Planned surgery can usually be performed laparoscopically. The diseased sigmoid colon is removed and the healthy ends of the bowel are joined. Under suitable conditions, the need for a stoma in planned surgery is lower than in emergency surgery.

How is diverticular bleeding treated?

A significant proportion of diverticular bleeds stop on their own. However, the amount and source of the bleeding must always be assessed.

Treatment may include:

• Blood tests and fluid support through a drip,
• Blood transfusion if necessary,
• Locating and stopping the source of bleeding with colonoscopy,
• CT angiography or angiographic embolisation,
• Surgery in selected cases that cannot be controlled.

Patients taking aspirin, blood thinners or painkillers should not stop their medicines on their own initiative; during the emergency assessment, they should tell the healthcare team about all the medicines they take.

Related operationLaparoscopic Colectomy →Read how the operation is performed and what recovery involves →

What should I eat after an attack?

During the acute painful phase, diet may be temporarily limited to fluids or low-residue foods, depending on symptoms. As the pain and nausea ease, a normal diet is gradually resumed.

Once the attack has completely passed, it is generally recommended to:

• Eat a diet rich in vegetables and fruit
• Eat whole grains and pulses as far as they are tolerated
• Take enough fluids
• Limit red and processed meat
• Maintain a healthy weight.

The amount of fibre should be increased gradually, not suddenly, according to bloating and wind. A high-fibre diet may not be suitable for patients with chronic narrowing of the bowel; for this reason, personal advice should be sought.

Are nuts, seeds and popcorn forbidden?

No. In the past it was thought that foods such as hazelnuts, walnuts, seeds, sesame and popcorn could get into the diverticula and cause inflammation. Current studies have not shown that these foods increase the risk of diverticulitis. If they do not cause noticeable complaints in the individual patient, there is no need to forbid these foods routinely [2].

Can the risk of recurrence be reduced?

No method can completely prevent diverticulitis from recurring. However, current scientific evidence shows that the following habits may help reduce the risk:

• A good-quality, high-fibre diet
• Regular physical activity
• Maintaining a healthy weight
• Stopping smoking
• Avoiding unnecessary and frequent use of non-steroidal painkillers

There is no sufficient and consistent evidence that probiotics or medicines such as rifaximin or mesalazine definitely prevent diverticulitis from recurring. The ACP guideline recommends that mesalazine should not be used to prevent recurrence [3].

1. Hall J, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Treatment of Left-Sided Colonic Diverticulitis. Diseases of the Colon & Rectum. 2020;63(6):728–747. doi:10.1097/DCR.0000000000001679. ASCRS guideline
2. Peery AF, et al. AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis: Expert Review. Gastroenterology. 2021;160(3):906–911.e1. doi:10.1053/j.gastro.2020.09.059. Access the publication
3. Qaseem A, et al. Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis and Colonoscopy After Diverticulitis: Clinical Guidelines From the American College of Physicians. Annals of Internal Medicine. 2022. ACP guideline summary
4. Schultz JK, et al. European Society of Coloproctology: Guidelines for the Management of Diverticular Disease of the Colon. Colorectal Disease. 2020;22(Suppl 2):5–28. doi:10.1111/codi.15140. ESCP guideline information