SEMINAR Diverticulosis of the colon is quite frequent in developed countries and prevalence rises with age. Although up to two- thirds of people older than age 80 years are affected, most remain asymptomatic. The causes of colonic diverticula include alterations in colonic wall resistance, disordered colonic motility, and dietary deficiencies, especially fibre. Clinical manifestations of this disorder range from non- specific intermittent abdominal pain to potentially life- threatening complications such as diverticulitis or haemorrhage. CT scanning and colonoscopy are important in diagnosis and management. Here, we review epidemiology, causes, clinical presentation, and manage- ment of diverticular disease of the colon. Epidemiology Prevalence of colonic diverticulosis is difficult to measure because most patients are asymptomatic. In early (1920–1940) autopsy and barium enema series, rates of 2–10% were reported. 1 Data show a substantial rise in colonic diverticula within the past few decades. Prevalence of diverticular disease increases with age, from less than 10% in people younger than age 40 years to 50–66% in patients older than age 80 years. 1–3 No sex differences seem to exist. Diverticulosis has been labelled a disease of western civilisation because of its striking geographic variability. The disorder is rare in rural Africa and Asia, with the highest prevalence seen in the USA, Europe, and Australia. 1 Within a given country, the incidence of colonic diverticula can vary in ethnic groups—eg, in Chinese inhabitants of Singapore, incidence was reported to be 0·14 cases per million population per year versus 5·41 cases in Europeans. 4 Urbanisation within a country over time can also lead to a rise in prevalence of diverticulosis. Follow-up in Singapore has indicated colonic diverticulosis in 19%, an increase Lancet 2004; 363: 631–39 See Personal account page 640 Division of Gastroenterology, San Francisco General Hospital, and University of California San Francisco, San Francisco, CA, USA (N Stollman MD); and Division of Gastroenterology, University of Miami School of Medicine, Jackson Memorial Medical Center, Miami, FL, USA (Prof J B Raskin MD) Correspondence to: Dr Neil Stollman, Division of Gastroenterology, San Francisco General Hospital, 1001 Potrero Avenue, Suite 3-D, San Francisco, CA 94110, USA (e-mail: NStollman@medsfgh.ucsf.edu) attributed mainly to dietary changes. 5 Results of series of symptomatic diverticular disease in Africa have shown a rising incidence in increasingly urbanised communities. 6,7 Cases of complicated diverticulitis have risen 50% in Finland in the past two decades, an increase attributed to an ageing population and reduced fibre consumption. 8 Although much of the epidemiological research mentioned is simply descriptive, understanding and assessing these noted trends could yield insight into pathogenesis of the disorder and help to predict disease course and complications. Pathological anatomy Colonic diverticula typically form in parallel rows between the taeniae coli because of weakness of the muscle wall at sites of penetration of the vasa recta supplying the mucosa. In European and US populations, diverticula arise mainly in the distal colon, with 90% of patients having sigmoid colon involvement and only 15% having right-sided diverticula. 3,9–11 This finding is in contrast to that seen in Asian populations, in which right-sided involvement is more prominent. 5,12 Diverticula vary from solitary findings to many hundreds. They are typically 5–10 mm in diameter but can exceed 2 cm. An entity of giant colonic diverticula has been described with sizes up to 25 cm. Most are single, located in the sigmoid colon, and asymptomatic, but can present with infection, obstruction, or perforation. 13 Diverticular disease of the colon Neil Stollman, Jeffrey B Raskin Seminar THE LANCET • Vol 363 • February 21, 2004 • www.thelancet.com 631 Colonic diverticulosis refers to small outpouchings from the colonic lumen due to mucosal herniation through the colonic wall at sites of vascular perforation. Abnormal colonic motility and inadequate intake of dietary fibre have been implicated in its pathogenesis. This acquired abnormality is typically found in developed countries, and its prevalence rises with age. Most patients affected will remain entirely asymptomatic; however, 10–20% of those affected can manifest clinical syndromes, mainly diverticulitis and diverticular haemorrhage. As our elderly population grows, we can anticipate a concomitant rise in the number of patients with diverticular disease. Here, we review the incidence, pathophysiology, clinical presentation, and management of diverticular disease of the colon and its complications. Search strategy and selection criteria Sources of information included: authors’ published work and research; and original research, reviews, and practice guidelines identified by computer database search—eg, MEDLINE, LexisNexis, The Cochrane Library, and Science Citation Index. Most recent publications were prioritised. Search terms included: “diverticulosis”, “diverticulitis”, “diverticular disease”, “diverticular hemorrhage”, “gastrointestinal bleeding”, “diverticular abscess”, “diverticular fistula”, “colonoscopy”, “endoscopy”, “epidemiology”, “pathogenesis”, “motility”, “fiber”, “computerized tomography”, “CT-scanning”, “surgery”, “laparoscopic”, “ultrasound”, “ultrasonography”, “barium enema”, “contrast enema”, “NSAID”, and “non-steroidal anti-inflammatory”, with Boolean operators AND and OR. Human and animal studies in the English language were reviewed and manually crossreferenced.