Diverticulitis - Symptoms, Causes and Treatment

Diverticula are small pockets or holes that form on the wall of the colon, usually in people over 60 years of age. Many people have diverticula in the colon without presenting any type of complaint or symptom.

The diverticula, however, can infect, leading to a picture called diverticulitis, which is common with fever, abdominal pain and changes in bowel habits.

Diverticulitis in large intestine
Diverticulitis in large intestine

What is a diverticulum?

A diverticulum is a small pouch that forms on the wall of the large intestine (colon), similar to a gloved finger, as can be seen in the illustration below.

A diverticulum is usually between 0.5 and 1 cm, and forms mainly in the final portion of the intestine (descending and sigmoid colon). Diverticula usually arise in the regions of the colon muscles where there are blood vessels. This information will be important when discussing part of the symptoms.

Any patient, who has at least one diverticulum identified as having a diagnostic test, whether radiologic or endoscopic, is considered to have diverticular disease, or simply, diverticulosis.

How do the diverticula appear?

Diverticula appear to arise from a weakness in the colon wall associated with years of increased pressure inside the bowel. The main risk factors are age, which favors the weakening of the bowel muscles, and a diet low in fiber, which in addition to encouraging intestinal constipation, also contributes to the formation of small and unformed feces, which increases the work the colon to push them toward the rectum and anus.

Other known risk factors are obesity and sedentary lifestyle.

Approximately 30% of people over 60 years and more than 60% of people over 80 years have diverticula.

What is diverticulitis?

The majority of patients with diverticulosis do not have any symptoms and often do not even know they have diverticular disease. Diverticulitis arises when one of the diverticula becomes inflamed. Diverticulitis = inflammation of the diverticulum.

It is now widely believed that the main cause for diverticulitis is obstruction of the diverticulum by small pieces of stool, which favor the proliferation of bacteria within the diverticulum.

There is no scientific evidence that eating peanuts, seeds, corn, popcorn or other foods of this size can cause obstruction of the diverticulum leading to diverticulitis. This is just a myth and patients with diverticula do not need to avoid this type of feeding.


Diverticulitis is often called "appendicitis on the left side". The symptoms can be very similar, since the pathological process is similar. In general, the symptoms are: malaise, severe pain in the lower left abdomen, fever, changes in the intestinal rhythm, be it diarrhea or constipation, nausea and vomiting. Eventually diverticulitis occurs on the right side of the intestine, a condition that is clinically indistinguishable from an appendicitis.

One of the possible complications of diverticulitis is the perforation of the inflamed diverticulum leading to contact of the intestinal contents (faeces) with the peritoneal cavity, which causes an intense peritonitis. Another dreaded complication is the formation of an abscess within the diverticulum, a condition that is difficult to treat and increases the risk of rupture of the diverticulum.

As noted at the beginning of this text, many diverticula form in areas where blood vessels pass, favoring their injury and the onset of bleeding in the intestine, manifesting clinically by the presence of blood in the faeces.

A more rare complication is the formation of fistulas, which is the appearance of a communication between two organs. For example, if diverticulitis occurs in an area of the bowel near the bladder, inflammation can cause these two areas to stick together and create a hole between them (fistula) causing urine to contact the bowel and stool with bladder.


Diverticulitis (colonoscopy)
Diverticulitis (colonoscopy)
Asymptomatic diverticula are usually discovered by radiological or endoscopic examination by chance. In most cases they are identified in colonoscopies performed for screening for colon cancer.

When ongoing diverticulitis is suspected, the best diagnostic test is computed tomography (CT) scan of the abdomen. In these cases, colonoscopy is usually done only after resolution of the inflammation for posterior evaluation and quantification of the diverticula. During the acute phase of diverticulitis, there is a fear that endoscopic procedures may worsen diverticulitis and facilitate perforations of inflamed areas.

The CT scan is capable of diagnosing not only diverticulitis but also abscesses and fistulas, if present. Ultrasonography can also be used as the first examination, before CT, for the ease and convenience of the procedure.


Patients with diverticulosis without symptoms do not need any treatment. Only changes in diet are indicated in order to consume more fiber in order to increase stool volume, which theoretically would reduce the risk of obstruction of the diverticula and prevent the formation of new lesions.

A mild diverticulitis can be treated at home with antibiotics and a diet restricted to liquids. In more severe cases with high fever, intense abdominal pain and inability to eat food, hospitalization and the use of intravenous antibiotics is necessary.

When there is no response to clinical treatment or when complications such as perforations and peritonitis arise, surgery for peritoneum lavage and removal of the diseased area of the colon is indicated. You usually have to have a colostomy for a few months to let the bowel heal.

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