Overall the mortality associated with diverticular disease very low. Only 1 in 100,000 people with diverticular disease dies as a result of complications of the disease. However a number of patients, perhaps 4 to 20% over a lifetime develop complications as a result of disease. Uncomplicated diverticulitis is the commonest complication. 

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It is believed that diverticulitis arises when a “nugget”  (fecalith) of stool becomes trapped in the mouth (or neck) of a diverticulum in patients with diverticular disease. This then causes irritation and further inflammation, this causes pain and sometimes altered bowel habit. People may complain of feeling generally unwell.  On occasion the inflammed mucosa may bleed. Sometimes such bleeding may be profuse, but is usually self-limiting. Such bleeding usually presents as rectal bleeding, commonly as blood mixed in the bowl with otherwise normal stools.  Diverticulitis may then take one of two courses. It can remain uncomplicated, settle, the pain resolves and people feel better. This may happen either with or without specific treatment such as antibiotics, this is known as uncomplicated diverticulitis. Alternatively it may be complicated by the development of abscesses, fistulae and perforation leading to sepsis and peritonitis. A few patients may develop diverticular associated strictures.

Segmental colitis associated with diverticular disease is a further form of diverticulitis associated with inflammtion within a segment of diverticular disease. This may be associated with stricturing as a consequence of the ensuing fibrosis and scarring within the colonic wall.

Abscesses occur when infection within a diverticula leads to the accumulation of pus in and around the “pocket” of the diverticulum. This then collects to form an abscess. Abscesses may require radiological or surgical drainage  or may resolve with antibiotic treatment. They may be complicated by fistulae or perforation. For more about treatment of diverticular disease click the link.