Digestive Health

Updated 21 May 2015

Diverticulosis and diverticulitis

Diverticulosis is a condition in which small sacs form on the wall of the colon.



The colon (large intestine) is a long, tube-like structure that stores and then eliminates waste material. As a person ages, pressure within the colon pushes bulging pockets or sacs of tissue (diverticula) outward from the colon walls. Diverticula can occur throughout the colon, but are most common near the end of the colon, namely the sigmoid colon. If you have this condition (diverticulosis), you may have few or no symptoms.

Diverticulitis occurs if a diverticulum becomes infected and ruptures. If you suffer from diverticulitis, you will have abdominal pain and tenderness, and fever. A diverticulum may also bleed.

When someone suffers the consequences of diverticulosis, it is referred to as diverticular disease.


Diverticula occur because of weaknesses in the bowel wall and increased pressure inside the bowel.

Connective tissue becomes weaker as a result of ageing, while the muscular wall of the colon grows thicker. This thickening may be a result of the increasing pressure required by the colon to eliminate faeces.

A diet low in fibre can lead to small, hard stools that are difficult to pass. Over time, vigorous contractions in the colon push the inner intestinal lining outwards through cracks in the muscle walls (herniation).


Uncomplicated diverticulosis is symptom free, and the condition may be found incidentally during tests for other intestinal problems.

The most common symptoms include abdominal cramps, constipation, diarrhoea and bloating. These symptoms are related to difficulty passing stools along the left colon when it has been narrowed by diverticulosis.

Symptoms usually occur due to a complication – most importantly, diverticulitis. About 20% of people with diverticulosis develop symptoms related to diverticulosis. This will cause continuous or cramping abdominal pain, usually in the lower left abdomen. Constipation and fever are common symptoms.

Pus may collect around the inflamed diverticulum, leading to the formation of an abscess, usually in the pelvis. On rare occasions, the inflamed diverticula can erode into the urinary bladder, causing bladder infection and passing of gas during urination. Inflammation in the colon may lead to bowel obstruction. Infrequently, a diverticulum ruptures into the abdominal cavity, causing a life-threatening infection (peritonitis).

Diverticular bleeding occurs when stool erodes into a blood vessel at the base of a diverticulum. Red, dark or maroon blood and clots are passed without any associated abdominal pain. Rarely, blood may be black in those bleeding from a diverticulum of the right-sided colon. Bleeding may be continuous or intermittent, lasting several days. In rare cases of brisk and severe bleeding, a drop in blood pressure may cause dizziness, shock and loss of consciousness.


Diverticular disease is common in the Western world, but extremely rare in Asia and Africa. The incidence of diverticular disease increases with age. It rarely occurs before the age of 30, but occurs in about 50% of people by the age of 70.


If diverticulitis is not treated, it may result in the formation of an abscess, which could lead to septic shock. A hole may develop in the wall of the bowel, leading to leakage of faeces into the abdomen and further infection. Small arteries may start to bleed (indicated by a change in stool colour), leading to iron-deficiency anaemia.

If there are no complications, keep in mind that there is nothing seriously wrong and that it is unlikely that complications will develop.

When to see a doctor

Call your doctor if:

  • Abdominal pain is severe
  • Pain is localised to one area of the abdomen and lasts longer than four hours
  • Abdominal pain is accompanied by a fever
  • Stools are dark red, black or tarry – this usually means there is blood in the stool, which needs to be evaluated.


Your doctor may perform the following investigations if he or she suspects that you may have diverticulosis:

  • Total blood count – to see if red blood cells have been lost and white blood cell count has increased
  • Abdominal and chest X-rays – to look for gas under the diaphragm, which indicates leakage of colon contents into the abdomen
  • Ultrasound examination – to detect an abscess
  • Barium enema – introduction into the colon of a fluid that can be detected by X-ray. Diverticula are seen as barium-filled pouches protruding from the colon wall.
  • Visual examination – a small tube is inserted through the rectum into the bowel. Short tubes (sigmoidoscopes) or longer ones (colonoscopes) may be used.
  • Ultrasound and computerised axial tomography (CAT) scans – if persistent pain and fever indicate a possible diverticular abscess, these examinations may be performed on the abdomen and pelvis to detect collections of pus.



Many patients with diverticulosis have minimal or no symptoms, and do not require any specific treatment.

A high-fibre diet and fibre supplements are advisable to prevent constipation and the formation of more diverticula. Keep your colon healthy:

  • Drink six to eight glasses of water each day.
  • Eat plenty of fruits, vegetables and whole-grain breads and cereals.
  • Add three to four tablespoons (45 to 60 g) of wheat bran to your daily diet.
  • Don’t strain during bowel movements.
  • Avoid laxatives.
  • Avoid drugs that slow down bowel action, such as painkillers containing codeine.

Some doctors recommend avoidance of nuts, corn and seeds to prevent complications of diverticulosis. Whether these diet restrictions are beneficial is uncertain.


Patients with mild symptoms of bloating or abdominal pain may benefit from anti-spasmodic drugs such as chlordiazepoxide, dicyclomine, donnotal, and hyoscyamine.

Antibiotics are usually needed. Oral antibiotics are sufficient when symptoms are mild. Commonly prescribed antibiotics include ciprofloxacin, metronidazole, cephalexin and doxycycline. People with severe diverticulitis accompanied by high fever and pain are hospitalised and given a combination of three drugs intravenously.


People with active bleeding are usually hospitalised for monitoring. Fluids are administered intravenously to maintain blood pressure. Blood transfusions are necessary for those with moderate to severe blood loss. Usually bleeding stops spontaneously and patients are sent home after several days in hospital.

Surgery is needed for people with persistent bowel obstruction or an abscess that does not respond to antibiotics.

Surgery is also indicated for severe bleeding, abscess drainage or when a hole has formed and colon contents are leaking into the rest of the abdomen. This often means that a part of the bowel has to be removed, but once healed, it normally does not cause additional problems, provided that the correct diet is followed.

Sometimes surgery may be suggested for people with frequent attacks of diverticulitis leading to multiple courses of antibiotics, hospitalisations and loss of workdays.


Once formed, diverticula are permanent, and there is no treatment available to prevent complications. However, the diet advised for home treatment may help prevent further diverticular formation or worsening of the condition.

Reviewed by Prof Don du Toit (M.B.Ch.B) (D.Phil.) (Ph.D) (FCS) (FRCS)


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Digestive Health Expert

Dr. Estelle Wilken is a Senior Specialist in Internal Medicine and Gastroenterology at Tygerberg Hospital. She obtained her MBChB in 1976, her MMed (Int) in 1991 and her gastroenterology registration in 1995.

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