Digestive disorders

II./2.3.: Diverticulosis

The diverticulum:

Diverticulum indicates a pouch, a blind sachet of different size, opening from a hollow organ’s wall, which can consist of all the original wall layers, or just some of the layers (e.g. mucosa). Its aetiology can be congenital or acquired.

Illustration 1.: Structure and surroundings of an acquired colon diverticulum(Balázs Kiss). (1)Tunica muscularis propria, (2) A diverticulum lumene, (3) A diverticulum elvekonyodott fala (4) Tunica serosa, (5) Béllumen, (6) A diverticulum szájadéka

• - A typical example of a congenital diverticulum is the Meckel-diverticulum, a residuum of the ductus omphaloentericus  located in the distal ileum, at 60-100 cm distance in oral direction from the Bauchin (ileo-coecal) valve (4d), including all the colonic wall layers . Ectopic tissue elements, such as duodenal, gastric or pancreatic pieces can often be part of the Meckel-diverticuli wall. These are possible sources of symptoms: peptic ulcer or pancreatitis might develop in them.

• - Acquired dicerticuli containing all wall layers of the original organ are common in the duodenum or jejunum. Commonly these are rounded pouches of a few cm size. Their opening towards the bowel lumen is usually broad, the tunica muscularis propria, present in their walls, is able to maintain the effective bowel movements, and the bowel contents are mainly thin and liquid at this point. Due to the above mentioned three factors, bowel content stagnates much less in these diverticuli as compared to the smaller colonic diverticuli. Thus bacterial overgrown and inflammation is missing, making duodenal and jejuna diverticuli peaceful lesions, free of inflammation and complications.

• - Another and most common example of acquired diverticuli is present in the colon, mostly in the sigmoid colon. Characteristically they are built of mucosa, protruding between the muscular colon walls. They lack a considerable muscle layer, as their tunica muscularis propria is missing. In the literature they are sometimes called pseudodiverticulum due to their incomplete wall structure, but in everyday clinical use they are simply called diverticuli, similar to the ones with complete wall layers, and we will also follow this practice here. They have a typical appearance: several protrusions in the size of 0,5-1,5 cm, following each other in a rope-like position. Their occurrence increases with older age. We will further discuss the characteristics of colonic diverticuli.

The state when several diverticuli is present in a hollow organ’s wall is called diverticulosis.

Illustration 2.: Diverticulosis(Balázs Kiss). (1) Haustra coli, (2) Tenia mesocolica, (3) Tenia libera, (4) Tenia omentalis, (5) Diverticulumok, (6) Diverticulumok szájadékai

Aetiopathogenesis (aetiology and pathogenesis) of colonic diverticuli is not unambiguous. Several factors has a role in their development, such as genetic and anatomical causes (weakening of bowel wall, e.g. due to entering veins)

 Nutritional factors, mainly lack of fibres in the diet  make the bowel content less plastic, thus increasing intraluminal pressure in the colon and leading to constipation, which has also a role in aetiology.

Faeces stagnates in the diverticulum’s cave, and without its own muscle wall the diverticulum can never vacate properly. This leads to clogging and dilatation; bacteria proliferates in the stagnating faeces, causing inflammation of the diverticulum mucosa (diverticulitis), extenuation and even perforation.

The latter can lead to the reoccurring acute and later, chronic inflammation of the surrounding tissue (peridiverticulitis),which in case of an exacerbation can meld into an abscess (abscessus pericolicus seu peridiverticularis). The spreading inflammation can reach the peritoneal mucosa of the affected colon stretch, causing localized or diffuse peritonitis (peritonitis circumscripta seu diffusa).

Moderate, reoccurring, subclinical peridiverticulitises may not show the above mentioned acute course, but lead to slow cicatrisation of the colonic wall

(fibrosis), resulting in the stenosis of the colon stretch. The stiffened colon wall has a restricted movement capacity, thus in the transmission of bowel content the diverticular colon stretch cots as a functional obstruction, leading to intestinal obstruction (subileus,.