Colonic diverticula - Classification

There are true and false diverticula. True diverticula are a protrusion of the entire intestinal wall, which contains the mucous membrane, muscular layer and serosa. They have a wide connection with the intestine and are easily emptied. Usually these are single diverticula, less often multiple. Inflammation in them develops relatively rarely, just as not all people develop appendicitis.

Pseudodiverticula are hernia-like protrusions of the mucous membrane between the muscle fibers of the intestinal wall. Graser (1898) and later Schreiber (1965) suggested distinguishing between incomplete and complete diverticula. Incomplete diverticula, also called intramural, represent the initial stage of the formation of false diverticula. Intussusception of the mucous membrane does not occur beyond the muscular layer. At this stage, the prolapse of the mucous membrane can be reversible. Diverticula are small sleeve-shaped canals. Sometimes they have a flat-expanded T-shaped bottom. Such diverticula are not reliably determined by radiography. They give the intestinal contour the appearance of saw teeth. However, this radiographic sign is nonspecific. Emptying such diverticula is difficult. The mucous membrane in a narrow channel is easily irritated, swells, and the entrance to the diverticulum closes. Stasis of infected contents in incomplete diverticula leads to chronic inflammation, often to the formation of intramural microabscesses. The tendency to inflammation is a feature of incomplete diverticula. They occur more often in groups.

Complete diverticula, or extramural, or marginal - this is a further stage of diverticulum development, when intussusception of the mucous membrane occurs through the entire intestinal wall. They are visible as protrusions or saccular formations on the intestinal surface and are easily detected by X-ray examination. The wall of a complete diverticulum consists of the mucous membrane, submucosa and serosa. The mucous membrane at the bottom of the diverticulum gradually atrophies under the influence of compression by the contents, the muscle fibers contained in it disappear. The contractility of the diverticulum wall decreases, evacuation of the contents from it is impaired, there is a risk of coprostasis and infection, necrosis of the diverticulum wall from pressure. The diverticulum wall is thin, which increases the risk of perforation and promotes the transition of inflammation to neighboring organs. These diverticula are often multiple, they can be combined with incomplete diverticula.

Localization of diverticula. The favorite localization of diverticula is the left half of the colon, primarily the sigmoid colon. In generalized diverticulosis, the number of diverticula usually decreases in the oral direction. In the right sections of the colon, including the appendix, single true diverticula often occur, which can be congenital (more often) and acquired.

More frequent damage to the left half of the colon is explained by anatomical and functional features, since it has a smaller diameter, has more bends, its contents are hard and it is more often subject to trauma. The sigmoid colon also has a reservoir function. Regulating the movement of feces, it is more often segmented than other sections, so the pressure in its cavity is higher. All this favors the occurrence of diverticula.

In the rectum, which also has high motor activity, the muscular layer is stronger than in the colon (the longitudinal muscle is not in the form of shadows, but solid). Diverticula in it appear rarely.

In residents of eastern countries (Philippines, Japan, China, Hawaiian Islands) right-sided localization of diverticula is much more common - it accounts for 30 to 60% of cases. At the same time, the average age of patients is at least 10 years younger. At the same time, in the Caucasus, left-sided bowel disease is typical for residents of the West. The cause of the "Asian variant" of diverticular disease is unclear.

Diverticula may be single or multiple, their size varies from a millet grain to a cherry, less often to a pigeon's egg. There are known cases of giant true diverticula of the colon. Thus, Zozzi described an observation in which a diverticulum 105 cm long was found in the area of the hepatic flexure of a patient.

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