Diverticular disease is very common in Western countries and it affects nearly half of New Zealanders over the age of 60.

What is diverticular disease?

Diverticular disease of the colon is a condition where the lining of the colon bulges through defects in its muscle wall, creating multiple pouches, or “diverticula”. Diverticular disease also affects the smooth muscle in the colonic wall, which becomes thickened and scarred. Within the colon diverticula are most commonly found on the left hand side, just above the rectum. Since these pouches seldom cause any problems most people will never know whether they have them or not.

What is Diverticulitis?

Occasionally a diverticulum becomes inflamed, resulting in “diverticulitis”, which means “inflammation of a diverticulum”. Diverticulitis can cause constant pain, usually in the lower abdomen, with a change in bowel habit (constipation, diarrhoea, mucus, or bleeding), and fever. 

Rarely a diverticulum will burst, allowing faecal material to escape from the colon. This can cause anything from a small abscess to life-threatening peritonitis (infection in the abdomen). Sometimes one of these abscesses will break through into an adjacent structure, such as bladder, vagina, or another part of the bowel. This causes a channel between the colon and the adjacent structure, which is known as a fistula.

What are the symptoms of diverticular disease?

Though most individuals with diverticular disease have no symptoms, some may experience:

• Urgent diarrhoea (due to intense colonic contractions or spasm)

• Uncomfortable abdominal bloating (due to poorly coordinated contractions)

• Cramping abdominal pain, especially on the left side

• Constipation

• Increased flatulence

• Blood in the bowel motions

The same symptoms can occur with colon cancer. Diverticular disease can mimic colon cancer, so you should not assume you have diverticular disease unless it is confirmed by colonoscopy or barium enema and colon cancer is ruled out.

What causes diverticular disease?

Diverticula form when strong but poorly co-ordinated contractions of the colon produce high pressure within the bowel. This pressure forces the lining out through weak points in the muscle wall of the colon, usually at the site where a blood vessel comes through. It is not known why the contractions are so intense or poorly co-ordinated, nor why the muscle becomes thickened. It is suspected that it may be due to toxins produced by bacteria digesting certain foods. Individuals with a life-long diet high in animal fats and low in fibre have a higher incidence of diverticular disease.

Once diverticula have formed they are permanent.

How is diverticular disease diagnosed?

Diverticular disease is diagnosed by colonoscopy or CT colonography. Colonoscopy is an examination of the inside of the colon with a video camera. CT colonography uses X rays to create a three dimensional picture of the colon. Diverticulitis is diagnosed by a clinical history and physical examination by your doctor, with a blood test to look for evidence of infection.  A CT scan or colonoscopy may be performed to find inflamed diverticula.

What are the complications of diverticulitis?

The most severe complication of diverticulitis occurs when an infected pouch ruptures, leaking faeces into the abdomen, and producing serious abdominal infection (peritonitis). This is a surgical emergency. Other complications of diverticulitis include blockage of the colon, the formation of an abscess, or the development of a fistula. A fistula is an abnormal passageway that connects that part of the inflamed bowel to bladder, vagina, skin or another part of bowel.

How is diverticular disease treated?

Symptoms are mild or absent

Individuals with mild symptoms from diverticular disease need not have any specific treatment. Mild symptoms may ease with careful attention to adequate fibre (at least 20 grams a day) and fluid (at least 2 litres a day) in the diet.

Symptoms are mild to moderate

More severe bloating and colicky pain can be aggravated by a high fibre diet, and for these people, a low residue diet can help. Medications are not universally effective, but antidiarrhoeal and antispasmodic drugs including Loperamide, Lomotil, Buscopan, Merbentyl, and Mebeverine, sometimes help.

Diverticulitis

Acute diverticulitis usually settles with rest and antibiotics. When symptoms are severe, admission to hospital may be necessary to give you intravenous fluids and high dose antibiotics. If symptoms are severe or do not settle within a few days, a CT scan may identify an abscess which should be drained. Dietary measures, including a high fluid intake and avoiding dietary fibre, seeds and nuts can help during an acute attack.

Perforation with peritonitis

This is a surgical emergency, and urgent operation is usually indicated to remove the perforated section of colon.

Recurring diverticulitis or chronic incapacitating symptoms

Surgical removal of the affected portion of colon is often the best long-term solution.

Surgery for diverticular disease

Surgical treatment for diverticular disease is the last resort, reserved for the following situations where medical treatment is inappropriate or has failed:

• Emergency conditions such as perforation

• Persistent or recurring diverticulitis

• Chronic debilitating symptoms including pain, urgent diarrhoea and constipation

• Fistula

The first objective of any operation for diverticular disease is to remove the affected section of colon. Except in the presence of severe infection, the colon can be joined back together again. However, if there is peritonitis, it may be necessary to create a temporary stoma (bowel empties into a bag on the tummy wall) to reduce the risk of further infection.

Frequently asked questions

Is diverticular disease common?

Diverticular disease is very common in Western countries and it affects nearly half of New Zealanders over the age of 60. It is more common with advancing age, being rare before the age of 30. Individuals who get diverticular disease young tend to have more aggressive disease with more severe symptoms. Only 15-20% of people with diverticular disease ever develop diverticulitis.

Does diverticular disease go away?

Once diverticula have formed they are permanent.

Is diverticular disease associated with cancer?

No. There is no link between diverticular disease and cancer. However, since diverticular disease and bowel cancer may cause similar symptoms it is important to establish the correct diagnosis by examination of the colon by colonoscopy or CT colonography.