- Diverticular Disease is characterized by the presence of usually multiple acquired diverticuli most commonly in the large intestine, especially the sigmoid Colon. "Diverticulosis" refers to the existence of such diverticuli in the absence of their inflammation whereas "Diverticulitis" refers to the inflammation of such diverticuli. It should be pointed out that diverticular disease only involves acquired diverticuli whereas there do exist special cases of congenital intestinal diverticuli, the most important being Meckel Diverticulum.
- Diverticular Disease is a pathology of the elderly and is highly common in those older than 60 years living in western developed countries.
- Diverticuli are classified as "True" or "False" depending on which histological layers surround the diverticular outpouching. True diverticuli are surrounded by all histological layers of the intestinal wall where as false diverticuli are only surrounded by the large intestine mucosa which herniates through the large intestine muscularis propria. For reasons described in the pathogenesis section, most diverticuli encountered in diverticular disease are of the false subtype and range between 0.5-1cm in diameter.
- Recall that the large intestine muscularis propria is unique in that it does not exist uniformly around the entire colonic wall, but exists as three longitudinal bands called the taeniae coli (See: Large Intestine Histology). Therefore, the colonic wall has somewhat less support than other parts of the alimentary tract. Tiny focal defects of the colonic wall occur where nerves and blood vessels penetrate through the large intestine muscularis propria. Peristaltic motions in the large intestine can generate intense spikes in the colonic intraluminal pressure causing herniation of certain layers of the intestinal wall and thus creating false diverticuli. It is thought that a western diet in particular enhances peristaltic intraluminal pressures due to reduced stool bulk, arising from a general lack of dietary fiber.
- Diverticuli can become inflamed or infected when particulate matter becomes retained within or obstructs the opening of the diverticulum.
- On its own, diverticulosis is typically asymptomatic but can result in occult or in some cases overt brisk lower GI bleeding. However, inflammation of diverticuli, resulting in diverticulitis, typically yield a left lower quadrant abdominal pain as well typical signs of infection such as fever, chills, and anorexia. Infection of diverticuli can extend into adjacent areas resulting in abdominal abscess or peritonitis. Untreated cases of diverticulitis can result in bowel perforation and surgical emergencies.