Chapter 8e
DIVERTICULAR DISEASE OF THE COLON
1. DEFINITION AND OVERVIEW
Diverticular disease of the colon is the most frequent disease of the colon in urbanized society. Essentially it consists of an outpouching of the colonic mucosa through the colonic wall, generally at the site of a potential defect where an arteriole passes through the wall. Diverticula are only found in the mesenteric border of the colon, the site of the blood supply. Very common, it increases in prevalence with age, reaching figures of around 50% by age 70 in western society. When present in an uncomplicated form it is termed diverticulosis attracting ICD 10AM Code is K57. There is a recent in depth review (1). Diverticulosis has unquestionably increased in prevalence in recent decades in urbanised societies. Before the mid 19
thcentury it was a curiosity in western societies as it still is in primitive societies. Osler’s Modern Medicine (1908) refers to it being found once in 2383 autopsies at Boston City Hospital. Studies have substantiated the rarity of diverticulosis in tribal societies. In Singapore it is much more frequent in Europeans than in ethnic Chinese in which it is clearly rising in prevalence as it is in recent years in urbanised communities in Africa. Diverticula predominate in the sigmoid colon and the prevalence falls of as we move proximally.
Strangely, the right colon is seldom affected in western society but is
reported to be the most frequent site in the East. The condition is relatively
benign and it is estimated that no more than 20% of those with it will
develop symptoms, possibly 1 in 200 will require hospitalization at some
stage and 1 in 10000 will die of it.
130 0 Chapter 8e
2. PATHOGENESIS
This is ill understood but is most likely related to a disturbance of structure and function of the muscular coat of the colon. There is generally a thickening of the muscular wall in relation to the herniated mucosa and submucosa. The longitudinal muscle is often contracted to produce a concertina-like pattern in proximity to the diverticulosis. There is good evidence that the intraluminal pressure is raised in the affected segment (2, 3). The proposed mechanism is that the thickened wall is associated with the impaired propulsive activity and increased compliance of the wall.
3. COMPLICATIONS
The major ones are infection and inflammation – diverticulitis and bleeding.
3.1 Diverticulitis
This most often originates in one of the diverticula in the sigmoid when inspissated faecal material sets up an inflammatory process in the wall but it seldom leads to free perforation though it may well produce a peri diverticular abscess.
3.2 Bleeding.
For obscure reasons this generally originates in the right colon with a minute rupture of a vessel in an uninflamed diverticulum. Once it happens further episodes are likely, and the bleeding may be quite dramatic.
Microscopic bleeding may also occur leading to an iron deficiency anaemia.
4. RISK FACTORS 4.1 Age
It is clear that the prevalence of diverticular disease rises with age.
4.2 Sex
The prevalence is equal in the sexes.
DIVERTICULAR DISEASE OF THE COLON 131
4.3 Diet
There is good evidence that the fundamental cause is the low fibre diet of affluent societies. It is much less frequent in vegetarians in the west as in people on a largely vegetable diet in the lesser developed world and there is good anecdotal and some scientific evidence of symptomatic relief with a high fibre diet.
4.4 Exercise
This is one of the most intriguing featuresf the disorders. In 47 678 American men aged 40 – 75 free of known diverticular disease, during four years of follow up 382 cases were found. After adjustment for age and energy adjusted fibre and fat intake, overall physical activity was inversely related to the risk; highest versus lowest RR=0.63(0.5-0.88), most attributable to vigorous activity. For extreme categories RR=0.60(0.41- 0.87). For those who undertook no vigorous activity RR=0.93(0.67-1.69).
Jogging and running combined was the only statistically significant individual activity (P trend = 0.03). For the lowest quintile of fibre intake and physical activity compared with the opposite extremes the RR was 2.65 (1.36-4.82); (4). Smoking, caffeine and alcohol intake were not associated with diverticular disease (5).
The suggestion that IBS leads to diverticulosis is unproven.
5. SUMMARY
Diverticular disease is one of the prices that mankind pays for pursuing an affluent urbanised lifestyle with clear evidence of a low fibre diet and lack of heavy physical exertion being major factors.
References
1. Stollman N, Raskin JB. Diverticular disease of the colon. Lancet 363,631-9 (2004).
2. Painter NS, Truelove S. The intraluminal pressure patterns in diverticular disease of the colon. Gut 5,201-3 (1964).
3. Arwidsson S, Koch N, Lehmann I, Winberg T. Pathogenesis of multiple diverticula of the sigmoid colon in diverticular disease. Acta Chir. Scand. Suppl. 342,1-68 (1964).
4. Aldoori WH, Giovannucci EL, Rimm EB et al. Prospective study of physical activity and the risk of symptomatic diverticular disease in men. Gut 36,276-82 (1995).
5. Aldoori WH, Giovannucci EL, Rimm EB et al. A prospective study of alcohol, smoking, caffeine, and the risk of symptomatic diverticular disease in men. Ann. Epidemiol. 5,221- 8 (1995).
