Diverticular disease (view from the inside - at colonoscopy). Note that the "pockets" are wide-mouthed

Viewed from the outside

What is diverticular disease?

• This is a condition where there are “pockets” on the colon.
  • These are “ballooned out” areas that form in weak spots on the colon presumably in response to high pressure in the bowel.
  • Diverticular disease is common - and becomes more common with age.
  • More than 1/3 of people over 45 years and 2/3 people over 85 years have diverticular disease.
    
    

• The cause of diverticular disease is unknown.
  • It is a disease that is much more common in Western populations.
  • It is uncommon in Asian and African populations.
  • This has given rise to the idea that the low dietary fibre in the Western diet is the cause of diverticular disease.
• This is only a hypothesis.  There is only limited evidence linking low fibre intake with diverticular disease.
• Large studies in European populations have shown that consuming a vegetarian diet and a high intake of dietary fibre were both associated with a lower risk of hospital admissions and death from diverticular disease.  In particular, it is fibre from fruits and vegetables that is protective.
• There is an association with being overweight and a sedentary lifestyle
• There is probably a genetic factor as there is commonly a family history.   A genetic factor is supported by twin studies that show a 4-7 fold risk.
• There is an association with a  high red meat diet and a high-fat diet.
• There is a modest positive association between smoking and diverticular complications.
  

What factors alter the risk of getting diverticulitis

• Both vigorous exercise and total physical activity decrease the risk of diverticular complications.
•  Obesity is a risk factor for diverticular complications. The association may be stronger for central obesity assessed by waist circumference.
• Nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, and opiates have been found to increase the risk of diverticulitis and diverticular bleeding.
• Aspirin intake two or more times per week increases the risk for diverticular bleeding and regular users of NSAIDs have an increased risk of diverticulitis and diverticular bleeding.
• There is a twofold increased risk of diverticular perforation in patients taking opioids and a threefold increase of perforation in patients on steroids.

Colonoscopy to diagnose diverticular disease

Symptoms and complications

• Diverticular disease can be present without any symptoms.
  • It may be found because of a colonoscopy performed for other reasons.
  • In this situation no treatment or change in diet is required.

• The most common symptom is lower abdominal cramping pain, particularly in the left lower abdomen.  This may be prior to or just after passing a bowel motion but can be at any time.
  • There is some overlap with symptoms from irritable bowel syndrome.
  • The cause of pain with diverticular disease is not well understood. It is partly because of enlargement of the muscle layers of the colon leading to more "spasm".
  • Equally important may be distension from trapped wind.
  • Overgrowth of bacteria may occur - with or without overt evidence of "diverticulitis" (see below).
  • Inflammation of the affected bowel can occur in the absence of infection. The cause of this associated inflammation is unknown.

• The bowel motions can alter in form and consistency.
  • Sometimes there is constipation with thin pencil-like motions.
  • Sometimes there is urgency and semi-formed motions.

Complications of diverticular disease

• The most common complication is rectal bleeding.
  • This is bleeding of sudden onset that lasts for 12 – 48 hours then settles without treatment.
  • Occasionally the bleeding can be brisk enough to cause faintness and there is enough loss of blood to require hospital admission and blood transfusion.
  • The risk of a further bleed is about 30% over the next 3-5 years.
  • Rectal bleeding (on the more regular basis) is more commonly due to piles or an anal fissure even if there is known diverticular disease.

• Diverticulitis - infection within the "pockets".
  • Infection within one of the pockets can cause more severe and prolonged pain that may last for several days (up to a week).
  • There may be marked tenderness in the left lower abdomen and sometimes fevers, sweats, nausea, loss of appetite.
  • A blood test may show some inflammation.
  • These infections can be recurrent.
  • Treatment by antibiotics (see below) although mild episodes may settle without treatment.

• Rarely the infection can create abnormal connections with other surrounding structures (fistula).
  • One example is a connection between the colon and the bladder.
  • This will give recurrence bladder infections and air in the urine.

View of diverticular disease - from the outside. This is the view at the time of laparoscopic surgery

Surgical specimen showing diverticular disease

Can the disease be prevented or can worsening of the disease be prevented?

• The usual advice is to increase dietary fibre intake.

  • The evidence for this approach is lacking but should at least be tried for a period. Some people with narrowing of the colon as a consequence of the diverticular disease may actually have more abdominal pain with increased dietary fibre.

  • A vegetarian diet has been shown to reduce the risk of complications. It seems that the cereal fibre or fibre supplements have no or limited protective benefit

• The advice to avoid nuts and seeds has no basis and is best ignored.

  • The pockets in diverticular disease are "wide mouthed" and it is unlikely that food contents lodge and cause episodes of infection.

  • In fact, there is no recorded case of blockage of a diverticulum by nut or seeds.

  • This commonly given advice is based on theory only (a dubious theory).

  • A study comparing diets with whole corn or without corn showed no difference in complications from diverticular disease

• A diet that reduces wind production may be sensible (see exclusion diet and low FODMAP diet).

What treatments are required?

• The pain in the lower abdomen may be relieved by anti-spasmodics.

  • The best medication is probably Colofac.

  • Alternative is Buscupan (Gastro-Soothe).

  • Side-effects such as “dizziness, drowsiness or feeling spaced out” limit the usefulness of this medication for some people.

  • Only some people get relief from this type of medication

• There is an overlap between diverticular disease and irritable bowel syndrome

  • This may be due to pre-existing IBS or may be due to increased visceral hypersensitivity associated with changes that cause diverticular disease.

  •  IBS is more likely with uncomplicated diverticular disease – particularly diarrhoea -predominant IBS. The onset of typical IBS or worsening of IBS may coincide with the development of diverticular disease.

• Possible treatments include all options that might be considered for IBS. 

  • Anti-spasmodics may have more of a role in this setting (Buscupan or Colofac). Low dose tricyclic anti-depressants (usually amitriptyline and nortriptyline) have a role in chronic pain management.

  • The appropriate dietary advice may be a low fibre, low FODMAP diet particularly if there is associated bloating and diarrhoea. 

  • If there is constipation then there should be gentle treatment with  Mg, kiwifruit, PEG solutions.

  • Diarrhoea is best managed with combination of Colofac and/or low dose Amitriptyline rather than loperamide which is likely to cause constipation even at low doses. 

  • The diarrhoea is this setting is not “true” diarrhoea but colonic irritability analogous to IBS. 

• Antibiotics.

  • This will be most helpful if there are clear signs of diverticulitis (as above).

  • The usual approach is to use Amoxil and Flagyl (metronidazole) for 1 week. 

  • Rarely, if the infection does not settle with tablets then admission to hospital is required for intravenous antibiotics.

  • Some people with milder symptoms do get an improvement with antibiotics. Perhaps 3-4 days of metronidazole (Flagyl) on an intermittent basis is reasonable.

  • There is a trend towards using less antibiotics for presumed diverticulitis based on some recent evidence showing no effect for less severe cases.  I now use anti-inflammatory medication for the bowel - usually Asacol 3 tabs twice daily for 2-3 months and a probiotic such as Inner Health Plus - for less severe episodes of pain or if the pain is intermittent over a longer period of time 

• The most accurate test for diagnosis of infection is an abdominal CT scan – but this is only needed for more severe infections.

• At some stage a colonoscopy is required but it is better to wait for 1-2 months to make sure the infection has settled.

What about surgery?

• Surgery is sometimes required for the complications of diverticular disease.

•  Removing the diverticular is not a successful approach if the only symptom is pain (from spasms).

• The surgery may be planned (for example after two episodes of bleeding or severe infections)

• Emergency surgery my be required because of uncontrolled bleeding or perforation of the bowel. In this situation it is not possible to join up the bowel at the time of the initial operation - a temporary colostomy or bag is required for a few months to allow for healing and complete resolution of infection.

• Elective surgery may be through a laparoscopic or “keyhole” approach but this depends on the individual situation.

• The risks of having a recurrent attack of diverticulitis has also been overstated. Earlier estimates ranged from 25% to 45%. It was assumed that recurrent episodes would become more complicated and therefore surgery was necessary to prevent these complications.

•  Recent studies have shown recurrence rates of 10-15% over 10-year follow-up. The chance of needing emergency surgery is less than 5% following an episode of proven acute diverticulitis.