Diverticulitis is an inflammation of small sacs of the intestinal mucosa of the colon. It often remains asymptomatic, but can also manifest itself through pain and can become life-threatening if a diverticulum tears and empties intestinal contents into the abdominal cavity. The disease can be divided into different stages. On the one hand, the disease is classified according to the clinical symptoms of the patient, on the other hand according to the findings of the colonoscopy and the imaging (CT of the abdomen).
Stage 0
Stage 0 is known as simple diverticulosis. The patient has no symptoms at all. During colonoscopy, only the small bulges (diverticula) of the intestinal mucosa are visible, but they are not irritated, i.e. not inflamed. Computer tomography of the abdomen shows the diverticula as small cavities filled with gas or contrast medium.
Stage I
Stage I is characterized by an uncomplicated acute diverticulitis. The patient usually feels pain in the (left) lower abdomen and may have a fever. In colonoscopy, the diverticula this time impress as reddened and swollen bulges of the intestinal mucosa. If contrast medium is added, spiculae (thorn-like contrast medium pull-outs) and a thickening of the intestinal mucosa appear. The thickened intestinal mucosa may also be visible in the CT.
Stage II
In contrast to stage I, stage II of diverticulitis is a complicated acute diverticulitis. This stage is divided into three subforms. If stage IIa is present, it is a so-called phlegmonous diverticulitis or peridiverticulitis.
The patient feels a strong pain in the abdomen under pressure, and the physical examination shows a defensive tension of the abdomen. In the lower abdomen a roll-like resistance can be felt. Usually the patient also has a fever.
During colonoscopy clear redness around the diverticular necks is visible. Using contrast medium, spiculae and a thickened intestinal mucosa can be observed as in stage I. The CT shows the thickened intestinal mucosa, as well as thickenings in the fatty tissue around the colon.
Stage IIb is given if there is an abscessing diverticulitis, a covered perforation or a fistula. An abscessed diverticulitis is a local accumulation of pus in the intestinal mucosa (abscess). In a covered perforation, a diverticulum is torn, but has not yet completely penetrated the abdominal cavity.
A fistula is present when a connecting passage between the diverticulum and the abdominal cavity has formed. The patient usually has a fever, a local peritonism (pain due to irritation of the peritoneum). A colonoscopy reveals the same findings as stage IIa.
Using a contrast medium, it can be observed whether there is a tear in the intestinal mucosa or intestinal wall. In this case, the contrast medium may leak from the intestinal lumen. An abscess becomes visible in computer tomography.
At this stage, one or more diverticula are finally completely ruptured, i.e. have broken through into the free abdominal cavity. This creates a direct connection between the intestine and the abdominal cavity. Patients have an acute abdomen, which is characterized by very severe abdominal pain, possibly shock symptoms and vomiting. A colonoscopy is not performed in such a clinical picture. Computer tomography reveals free air in the abdominal cavity, which comes from the intestine, as well as free fluid and possibly abscesses.
