Definition of diverticulosis and diverticular disease

Diverticulosis is defined by the presence of diverticula. Diverticula are herniations of the colonic mucosa thought to form as a result of high intraluminal pressure, which forces the mucosa through the muscle layer of the bowel at points where it is weakened by penetration of a colonic artery. This pressure may be caused by the increased muscular contraction required to propel less bulky stools in people consuming a low-fibre diet.

Most diverticula occur on the left side of the colon (ie in the sigmoid and descending colon) but any part of the bowel can be affected. Right-sided diverticulosis is more common in Asian populations than in Caucasian populations, and in younger patients.

The incidence of diverticulosis increases with age, affecting approximately half of people older than 80 years. Diverticulosis is more common in females than males.

Diverticulosis is usually asymptomatic. Diverticular disease occurs when diverticulosis becomes symptomatic, and includes diverticulitis, local perforation and abscess formation, generalised perforation and peritonitis, obstruction due to strictures, fistulas and diverticular bleedingTursi, 2014Hall, 2020. A minority of patients have symptomatic uncomplicated diverticular disease, characterised by colicky lower abdominal pain or an irregular bowel habit (commonly alternating between constipation and diarrhoea). These symptoms cannot be distinguished from those of irritable bowel syndrome, and can be treated in the same way (see Irritable bowel syndrome).