ESSENTIALS OF DIAGNOSIS
Radiographic or endoscopic demonstration of diverticula.
Normal vital signs and laboratory evaluation.
Absence of complications (diverticulitis, diverticular hemorrhage).
Diverticula are acquired herniations of the colonic mucosa and submucosa through the muscularis propria. They occur most commonly in the sigmoid colon and can vary in size and number, although typically they are between 5 and 10 mm in diameter. Diverticulosis refers to the presence of diverticula in an individual who is asymptomatic, whereas diverticular disease refers to the presence of diverticula associated with symptoms, which occurs in 20% of individuals with diverticula.
Diverticular disease is the most common structural abnormality of the colon. It is estimated to affect 2.5 million individuals in the United States. In terms of health care expenditures (both direct and indirect costs), it is the fifth most important gastrointestinal disease in Western countries, representing total annual expenditures in the United States of over $3 billion. It accounts for approximately 3.2 million office visits and for more than 815,000 hospital admissions annually in the United States, with a mortality rate of 2.5 per 100,000 persons per year.
Although diverticula were described as early as 1700, diverticulosis was uncommon until the 20th century. Currently, it is estimated that diverticulosis affects less than 5% of people at age 40, 30% of people by age 60, and 50–65% of people by age 80. An exception to this is in vegetarians, in whom the prevalence of diverticulosis is much lower, presumably due to diets that are higher in fiber. Men and women are affected equally. The prevalence and distribution of diverticula vary throughout the world. Whereas diverticula are common and predominantly left-sided in Western countries (95% involve the sigmoid colon), in urbanized areas of Asia, such as Japan, Hong Kong, and Singapore, the prevalence is only 20% and the diverticula are predominantly right-sided, even among those who have adopted a Western-style, low-fiber diet.
Segmentation within the colon is thought to play an important role in the development of diverticula. Segmentation refers to the process by which a short segment of the circular muscle of the colon contracts in a nonpropulsive manner. This produces a closed segment of colon with increased intraluminal pressure, and likely serves to increase water and electrolyte absorption from the colon. These elevated intraluminal pressures may ultimately result in herniation of the mucosa and submucosa at sites of weakness (namely, where the vasa recta penetrates the muscularis propria between the taeniae coli), resulting in the formation of diverticula. Diverticula are not seen in the rectum because the taeniae coalesce at the rectum to form the circumferential longitudinal muscle layer.
The law of Laplace (transmural pressure gradient equals the wall tension divided by the radius, ΔP = T/r) may help to explain ...