The large bowel, or colon, is responsible for reabsorbing water from the faeces, which go from being liquid to solid as they pass clockwise through the colon to reach the rectum. With a Western diet, the stools are less fibre-filled and take more pushing to get them round to the rectum – as with squeezing a toothpaste tube, the colon has to push harder when it is almost empty. At many points in the colon, little blood vessels pass through the outer wall, creating weak points. With the excess pressure demanded by the Western diet, little outpouchings form at these points. These are known as diverticuli, and having them is referred to as diverticular disease. This is present in maybe as many as half of all Westerners over 50, and in most cases causes no symptoms. However, if these diverticuli become inflamed or infected – diverticulitis – then, much in the manner of the appendix, they can cause problems.

Diagnosis and Initial Treatment

Diverticulitis most commonly occurs in the sigmoid colon – the part on the lower left side of the abdomen shortly before the rectum. It often causes pain and tenderness here, along with fever, nausea, vomiting, bloating, diarrhoea or constipation, and may result in rectal bleeding.

All cases of diverticulitis are treated with antibiotics and put on a fluids-only diet in order to rest the colon. An abdominal x-ray and a CT scan of the colon may be sought early on to aid diagnosis and determine the severity of the disease. Individuals with mild disease will recover after 24–48 hours and can move to a 'low residue' diet, building up to a full fibre-containing diet once fully recovered. Given the age group affected, it is common to examine the colon using a special telescope (colonoscopy) once symptoms have settled down, in order to rule out any sinister problems.

An Emergency?

Diverticulitis represents an emergency in the cases where the infection does not settle. A collection of pus (abscess) may form, and the diverticuli may even rupture, allowing infected pus or faecal material into the abdomen. In these cases emergency surgery is warranted, to remove the offending section of bowel. The common approach is a Hartmann's operation, where the bowel upstream of the removed section is brought out to the skin to form a colostomy¹, while the bowel downstream from the removed section is closed over. In around a third of cases, the individual is suitable for a further operation to rejoin the bowel around six months later. The alternative to a Hartmann's would be removing the offending bowel and then joining up the ends straight away, which is liable to fail as the joined ends will be still be infected with pus or faecal material.

Summary

Diverticulitis is the inflammation and infection of outpouchings of the large bowel, causing pain, bleeding and bowel symptoms. It is sometimes treatable with antibiotics and bowel rest, but severe cases require urgent surgery.

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