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In diverticulitis, protrusions of the colon mucosa (diverticula) become inflamed. It mainly occurs in older people and can be harmless or life-threatening.

The walls of the colon consist of several layers. If the inner layers, the mucosa and the submucosa, push through gaps in the muscle layers of the intestinal wall, protrusions, so-called (pseudo-)diverticula, can form. If all wall layers of the intestine, including the musculature, pass through the muscular gap, this is referred to as a true diverticulum. If diverticula are asymptomatic, they are called diverticulosis. If such a diverticulum becomes inflamed, diverticulitis or diverticular disease develops. If the inflammation remains limited to the diverticulum, it is called peridiverticulitis. If the surrounding intestinal tissue is also affected, it is called pericolitis.

Diverticulitis is classified according to the CDD (Classification of diverticular disease) for diverticular diseases:

  • Type 0: asymptomatic diverticulosis
  • Type 1: acute uncomplicated diverticulitis
    • Type 1a: without phlegmonous environmental reaction
    • Type 1b: with phlegmonous environmental reaction
  • Type 2: acute complicated diverticulitis with
    • Type 2a: microabscess ≤ 1 cm in diameter
    • Type 2b: macroabscess >1cm
    • Type 2c: free perforation
    • Type 2c1: purulent peritonitis
    • Type 2c2: fecal peritonitis
  • Type 3: chronically recurrent or persistent symptomatic diverticular disease
    • Type 3a: symptomatic uncomplicated diverticular disease
    • Type 3b: recurrent diverticulitis without complications
    • Type 3c: recurrent diverticulitis with complications
  • Type 4: Diverticular hemorrhage

The classifications according to Hansen and Stock or Hinchey are still used in some cases. However, both classifications have been considered obsolete since the publication of the first guideline on diverticular disease/diverticulitis in 2014.

Epidemiology

Diverticula are considered a widespread disease in western industrialized nations. There are hardly any reliable figures on the incidence of diverticulosis and diverticulitis, as many diverticula do not cause any symptoms and are only discovered as incidental findings during colon examinations with contrast medium or in autopsies. This could lead to an overestimation of the frequency:

According to projections, diverticula in the colon are found in

  • approx. 13% of people under the age of 50
  • approx. 30% of 50 to 70-year-olds
  • around 50% of 70 to 85-year-olds
  • approx. 66% of over 85-year-olds

20-30% of patients with diverticula develop symptoms and diverticulitis in the course of their lives. Calculated on an annual basis, this affects around 4% of patients with asymptomatic diverticulosis. older patients are more frequently affected than younger ones. In Europe and America, the sigmoid, the last part of the large intestine, is particularly frequently affected. As the symptoms are similar to those of appendicitis, diverticulitis in this area is colloquially referred to as "left-sided appendicitis" or "left-sided appendicitis". In Asia, the ascending colon is more frequently affected, known as coecum diverticulitis. It is rarer, usually congenital and is caused by true diverticula.

Causes

Diverticula are considered a disease of civilization in Western populations. Triggers for diverticulitis are varied and often cannot be clearly defined. Increasing age appears to be one reason why diverticula develop. According to current studies, diet also plays an important role in whether or not a person develops diverticula and whether or not diverticulitis can develop as a result.

In particular, a low-fiber diet and a lot of red meat are being discussed as possible causes or promoting circumstances for diverticulosis. Smoking, obesity and a lack of physical activity can also promote the development of diverticula. If there is also stool congestion, the affected areas of the bowel become inflamed more quickly and diverticulitis develops.

Certain diseases such as diabetes, arterial hypertension, kidney disease, immunosuppression and allergic predispositions can also promote diverticulitis. Genetic factors such as Marfan syndrome can also cause diverticulitis.

Pathogenesis

The intestinal wall consists of several layers: the mucous membrane (mucosa), the submucosa, the muscle layers (muscularis) and the outer adventitia. Particularly in areas where blood vessels run through the intestinal wall, the so-called vasa recta, weak points can form. This increases with age as the connective tissue loses elasticity and the intestinal wall becomes increasingly less resistant to pressure. If constipation occurs repeatedly, parts of the intestinal mucosa are pushed through these gaps in the muscle tissue. The intestinal wall bulges out and diverticula develop.

If only parts of the intestinal mucosa protrude through the vascular gaps in the muscular part of the intestinal wall, this is referred to as a pseudodiverticulum. If all layers of the wall are affected, it is a complete, extramural diverticulum. As the sigmoid colon in particular is permeated by vasa recta and the pressure within the intestinal walls and from the inside of the intestine is very high here, these areas are particularly susceptible to diverticula.

The protrusion of the intestinal wall compresses the blood vessels supplying the intestinal wall. The blood supply to the diverticula deteriorates and the mucous membrane is undersupplied. If stool gets stuck in the diverticulum area, germs can attack the mucous membrane. The increased pressure from the stool also mechanically irritates the intestinal wall and can cause pressure ulcers (ulcers caused by pressure). The intestinal wall becomes inflamed and diverticulitis develops. If this happens repeatedly, the tissue fibroses. The wall thickens, the intestine is constricted at the affected area and a complete or incomplete intestinal obstruction occurs. In rare cases, the inflammation can also spread to neighboring intestinal loops and trigger a subileus or even an ileus.

In addition to the risk of intestinal obstruction, the inflammation in diverticulitis also increases the risk of abscesses, intestinal perforations and fistula formation. The thin intestinal wall can no longer withstand the pressure from the inside of the intestine and tears. If there are intestinal loops or parts of the intestinal wall over the torn area, this is referred to as a covered perforation, from which abscesses can form. If the intestinal wall tears and a hole forms, it is a free perforation. Intestinal contents can leak into the abdominal cavity and cause peritonitis. In this case, it is an acute surgical emergency with signs of peritonitis.

Symptoms

The clinical symptoms of diverticulitis depend on the place of origin. In Western countries, the symptoms of sigmoid diverticulitis are overrepresented with more than 90%. Its symptoms often resemble those of appendicitis, hence the colloquial name "left-sided appendicitis" or "left-sided appendicitis". All or only some of the following symptoms may occur:

  • Spontaneous pain, sometimes radiating to the back
  • Stool irregularities with constipation and diarrhea
  • nausea
  • Vomiting
  • Flatulence (bloating)
  • sometimes painful urge to defecate (tenesmus)
  • palpable painful pressure roller in the left lower abdomen
  • increased temperature
  • additional spastic stenosis in chronic cases

In coecal diverticulitis, on the other hand, pain occurs mainly in the right middle and lower abdomen.

If an inflamed diverticulum ruptures and a free perforation occurs, symptoms of acute peritonitis with sepsis are also present. These include

  • a high level of tension in the abdomen
  • severe pain
  • Fever, chills
  • nausea and vomiting up to coma and death.

Particularly in older, geriatric patients or immunocompromised patients, diverticulitis can also take an atypical course or acute symptoms may be completely absent.

Diagnosis

Diverticula are often asymptomatic. Only diverticulitis can cause symptoms. For this reason, the physical examination, but above all the laboratory examination and instrumental diagnostics are of great importance in diverticulitis. The medical history should include risk factors such as smoking, medication use (NSAIDs, corticosteroids, opiates and other drugs that increase the risk of bleeding) and eating habits.

During the physical examination, a painful roller can sometimes be felt in the left lower abdomen - the sigmoid colon is sensitive to pressure pain and occasionally distended. On percussion (tapping), a tympanic tapping sound is heard. similar to appendicitis, a release pain in the lower abdomen and a localized pressure pain may occur. If the diverticulitis is perforated, an acute abdomen with abdominal tension and severe tenderness are also possible. In the case of sigmoid diverticulitis, the pain may be movement-dependent and intensify with certain movements.

As diverticulitis can perforate, blood pressure and pulse should be checked if this is suspected in order to recognize a possible shock index at an early stage.

Laboratory: The laboratory mainly shows non-specific signs of inflammation with elevated CRP above 5 mg/100 ml, leukocytes above 10-12 000/μl and a erythrocyte sedimentation rate above 15 mm/hour. If the CRP is more than 20 mg/100 ml, the diverticulitis may already be perforated.

Imaging

Ultrasound diagnostics: Sonography is suitable for primary diagnosis as it is widely available, fast and can be used cost-effectively. It is also used in the follow-up diagnosis of diverticulitis and diverticulosis. It is carried out in accordance with the 2014 guidelines at ≥ 3.5 MHz (optimally > 5 MHz) and with dosed pressure on the area with the most severe pain. Sonography shows a low-echo, initially asymmetrical wall thickening of more than 5 mm. The wall stratification is abolished. The intestinal structure can only be slightly compressed or deformed under pressure. Around the inflamed diverticulum, an echogenic reticular cap with low-echo inflammatory tracts may have formed. Other characteristic features are the cross-section similar to a shooting target, the dome sign and inflammatory hypervascularization. Signs of an abscess include low-echo or anechoic foci in the wall or around the bowel, reverberation echoes and comet tail artifacts. In the case of free perforation, free air or echogenic fluid is visible in the abdominal cavity.

Computed tomography: If the diverticulum is located very deep in the abdominal cavity or if there is an emergency situation, sonography is not sufficiently diagnostic. CT is superior to sonography in terms of accuracy, especially in these special cases. It is the safest and most accurate method for detecting diverticulitis, but has the disadvantage of radiation exposure. Especially when abscesses or perforations are suspected, it provides rapid results and allows a solid staging and clarification of the question of the indication for surgery. Imaging shows an inflamed, swollen intestinal wall and fatty tissue bimbifications. In the case of perforation, free air can also be seen in the abdominal cavity.

Colonoscopy and endoscopy: Acute diverticulitis can sometimes be treated conservatively. In order to rule out other causes and to plan possible further treatment steps, a colonoscopy should be performed after the diverticulitis has subsided around 6-8 weeks after the illness. During the acute process, the intestinal walls are more sensitive. Therefore, the colonoscopy should only be performed after the inflammation has subsided. However, a colonoscopy should always be performed after the inflammation has subsided, as carcinomas may also be behind the inflammation. If blood is present in the stool, an endoscopy is often performed even during acute diverticulitis. This is necessary to find the source of the bleeding and to rule out causes other than diverticular bleeding.

Therapy

Diverticulitis therapy depends on the stage of the disease. Types 1a and 1b can usually be treated conservatively, the other types sometimes require surgery.

Conservative therapy

Uncomplicated acute diverticulitis can usually be treated on an outpatient basis. In addition to a broad-spectrum antibiotic, attention should be paid to a low-fiber diet until the symptoms subside. A low-molecular formula diet that is easily absorbed in the small intestine can also help. Paracetamol can be offered to relieve the pain.

The symptoms usually disappear within two to four days. As soon as symptoms are relieved and the infection parameters have decreased, the diet can be slowly rebuilt and a high-fiber diet can be introduced.

Type 2a should be treated as an inpatient. Nutrition is exclusively intravenous. The broad-spectrum antibiotic is also administered intravenously and should be selected so that it is primarily effective against anaerobes and gram-negative bacteria, for example metronidazole and ciprofloxacin or piperacillin and tazobactam/ceftriaxone. As conservative treatment is no longer always effective at this stage, the patient must be closely monitored.

In stage 2b, acute complicated diverticulitis, a percutaneous drainage can also be inserted. The symptoms should improve within two to three days. If this is not the case, or if there are signs of free perforation (transition to type 2c), sepsis or an acute abdomen, surgery is indicated.

Prognosis

The prognosis of diverticulitis depends on the age at which it first occurs and how severe it is. Nowadays, surgery is only generally indicated under special circumstances and in cases of perforation. It is difficult to say how often diverticulitis recurs and develops recurrences. If it is uncomplicated and can be successfully treated conservatively, the annual risk of recurrence is only 2%. However, it can also be as high as 30%, depending on the patient's age, severity and response to treatment. The risk of death also depends on the stage and the general condition of the patient. In stages 1a and 1b as well as 2a, it is less than 15%, whereas in stage 2c it is up to 15%. Early treatment is therefore important.

Prophylaxis

The risk of diverticula and diverticulitis increases with age. However, it can also be positively influenced by your own behavior. A high-fiber diet, for example, can help to keep the bowel healthy and prevent constipation. Physical activity also prevents diverticula, as does a healthy body weight. Quitting smoking also helps to prevent diverticula from becoming inflamed and perforating.

Note: Freely perforated diverticulitis is an emergency situation. It is an indication for emergency surgery.