Diverticular disease (diverticulosis and diverticulitis)

A colonic diverticulum is a sac-like protrusion of the colonic wall. The presence of many diverticula is called diverticulosis. In some cases, the diverticula may become inflamed, in which case the condition is called diverticulitis and occurs in approx. 10% of people with diverticulosis.

Diverticulosis is usually asymptomatic, but it may cause symptoms like abdominal pain or lower GI tract bleeding. Diverticular disease refers to symptomatic diverticulosis or diverticulitis. 10-25% of people with diverticulosis will develop diverticulitis at some point. It's a common cause of hospital admission.

Diverticular disease is mostly a disease of elderly. 60% of people at the age of 60 have diverticulosis. Diverticulosis and diverticular disease are more common in the West, likely due to our eating habits. In the Western world, diverticulosis predominantly affects the left colon, while in Asia, it predominantly affects the right colon.

Complicated diverticulitis refers to diverticulitis which has caused a local abscess, perforation, or peritonitis.

Etiology and pathomechanism

Colonic diverticula develop under conditions of high intraluminal pressure in the sigmoid colon, and since the colon has the muscle layer gathered at some places as teniae coli, this increased pressure may result in diverticula in these weaknesses where the muscle isn’t present. Exaggerated peristaltic contractions due to diet low in fibre may lead to high luminal pressure. In the western countries, as many as half of the population over 60 years may have this, while the prevalence in Japan and developing countries is much lower. This difference is due to the reduced fibre intake in the well-developed countries.

To avoid the development of diverticulosis, its recommended to eat dietary fibre (fresh fruits and vegetables, pasta etc.) and to have your feet elevated when sitting on the toilet.

The vessels of the diverticula become stretched and therefore weakened, which predisposes to the bleeding which presents are diverticular bleeding.

Diverticulitis occurs due to obstruction of the diverticular ostium by stool or foodstuffs, which causes inflammation.

Complications

The inflamed diverticulum may perforate due to erosion of the diverticular wall by increased pressure and food particles. The perforation is usually contained by pericolic fat and mesentery, causing only a simple localised inflammation, in which case this is known as diverticulitis with contained (or confined) perforation. However, in rare cases, the perforation is not contained, which may cause abscess, bowel obstruction, large perforation or fistula may occur (complicated diverticulitis), which may lead to peritonitis.

Clinical features

Diverticular bleeding is one manifestation of diverticular disease. This bleeding may be occult (discovered by a screening test) or acute, manifesting as haematochezia.

Diverticulitis typically presents with left sided abdominal pain, especially in the left lower quadrant (the location of the sigmoid), and low-grade fever. The pain usually lasts for multiple days. Patients may also have nausea/vomiting or recent change in bowel habits.

Patients with complicated diverticulitis may present with ileus, haemodynamic instability, or downright shock. The patient will be peritonitic in the left lower quadrant.

Patients with diverticulitis have a high risk of recurrent bouts of diverticulitis.

Diagnosis and evaluation

CRP and WBC may be elevated in diverticulitis, but not always.

Abdominal CT with contrast is the first choice for imaging and to establish the diagnosis. CT will also show any complications of diverticulitis.

Treatment

Asymptomatic diverticulosis requires no treatment.

Uncomplicated diverticulitis usually requires no specific treatment as it resolves on its own. Oral analgesics, a liquid diet, and laxatives to keep the stool soft alleviates symptoms while waiting for resolution.

Complicated diverticulitis should be treated as uncomplicated but with the addition of antibiotics. In Norway ampicillin + gentamicin + metronidazole are used. Larger abscesses should be drained.

Perforated diverticulitis or diverticulitis leading to colon obstruction must be treated with surgery.