Diverticulitis: when small pouches in the colon get infected

What it is, in plain words

With age, small pouches called diverticula push out through weak points in the wall of the colon. Having them is called diverticulosis and is common and harmless. When one becomes inflamed or infected, you have diverticulitis, which causes pain, usually low on the left side.

Signs to look out for

• Persistent pain in the lower left abdomen, building over a day or two
• Fever and chills
• Change in bowel habit, constipation or diarrhoea
• Nausea, bloating and loss of appetite
• Urinary symptoms if the inflamed segment lies against the bladder

Why it happens

Low dietary fibre, constipation, age, obesity, smoking and regular anti-inflammatory painkillers increase risk. The old advice to avoid nuts, seeds and popcorn has been disproved and is no longer given.

How doctors confirm it

CT of the abdomen is the reference test: it confirms the diagnosis and shows complications such as abscess or perforation. Blood tests show raised inflammatory markers. A colonoscopy is arranged several weeks later to exclude other causes.

Treatments and solutions

• Mild uncomplicated attacks: rest, clear fluids then gradual reintroduction of food, and often no antibiotics at all in healthy people
• Antibiotics for immunosuppressed patients, significant fever, raised markers or comorbidity
• Hospital admission with intravenous antibiotics for complicated disease
• Radiologically guided drainage of an abscess
• Surgery for perforation, obstruction, fistula, or repeated disabling attacks

Living with it day to day

Between attacks, build up fibre gradually to about 30 g a day with vegetables, fruit, pulses and whole grains, drink enough water, exercise, stop smoking and keep weight in a healthy range: this measurably reduces recurrences.

When to seek medical help

Seek urgent care for severe or spreading abdominal pain, high fever, inability to pass wind or stool, or vomiting.

This article explains general health information in simple language. It does not replace advice from your own doctor.