Diverticula in the Intestine: Understanding the Symptoms of Diverticular Disease, Diverticulosis, and Diverticulitis When Pouches in the Large Intestine Become Inflamed

The presence of diverticula is very common in Western countries. When multiple diverticula are present in the large intestine without inflammation, the condition is called diverticulosis. This form remains asymptomatic in most people. Only when food debris becomes trapped in the pouches and bacteria trigger an infection do the diverticula become inflamed, leading to diverticulitis. In this case, the risk of complicated diverticulitis is increased, which requires prompt medical intervention.

Diverticula are outward protrusions of the wall of a hollow organ. They can occur throughout the digestive tract. Most often, however, diverticula develop in the left side of the large intestine. The urinary tract (ureter, urethra, bladder) and, in very rare cases, the heart can also be affected.

Depending on whether all or only some of the wall layers are involved in the protrusion, a distinction is made between

• true diverticula (all wall layers are everted outward) from
• false diverticula, also known as pseudodiverticula (usually only the mucosa lining the intestine and the underlying submucosa are involved).

In most cases of diverticula, they are pseudodiverticula. This article therefore focuses primarily on pseudodiverticula.

The term “diverticulosis” is defined by the presence of what are usually multiple diverticula. If the diverticula cause symptoms, the condition is referred to as diverticular disease. If one or more diverticula are inflamed, the condition is called diverticulitis.

The presence of diverticula in the intestine and their severity can be classified into different categories. These classifications are important for determining the therapeutic approach.

If the diverticula are not inflamed, this is classified as Type 0, or asymptomatic diverticulosis. Inflamed diverticula, known as diverticulitis, can be classified into Types 1 through 4.

Diverticula in the intestinal wall can cause inflammation, and the intestine may even rupture © Henrie | AdobeStock

The question “How do diverticula develop?” can usually be answered by a combination of age and lifestyle. Over the years, the intestinal muscles lose elasticity. If there is also high pressure in the intestine—such as from straining during constipation—the mucous membrane protrudes outward through small gaps in the muscle layer. These protrusions in the intestine tend to form in the sigmoid colon (also called the colon sigmoideum), the S-shaped section of the large intestine just before the rectum. This area is particularly prone to diverticula because it bears the highest pressure.

In the remaining 30 percent of cases, various symptoms may develop depending on the stage of the disease:

• bloating, a distended abdomen, a feeling of incomplete bowel emptying—though these symptoms usually improve after a bowel movement—
• changes in stool consistency (primarily constipation),
• changes in bowel frequency,
• sometimes severe intestinal bleeding (diverticular bleeding is the most common cause of bleeding from the gastrointestinal tract),
• pain in the lower left abdomen ranging from mild to severe abdominal pain, as well as
• a palpable, cylindrical, firm mass, or even a “board-like abdomen”

A doctor must be consulted immediately, especially if there are signs of acute diverticular disease. Signs include pain in the left lower abdomen and abdominal distension.

This pain is caused by the inflammation spreading to the outer surface of the intestine and to the peritoneum. This results in peritonitis.

As diverticular disease progresses, it can lead to

• puss-filled pockets (abscesses) and even
• perforation (tearing) of the intestine

. This allows stool and gas to escape from the intestine into the abdominal cavity. This “fecal peritonitis” can still be fatal even today, despite surgical treatment and antibiotic therapy.

If inflammation—even mild inflammation—recurs repeatedly, the condition is referred to as chronic diverticular disease. Over time, this can lead to atrophy of the intestine and the development of a narrowing (stenosis) in the intestine.

As long as the diverticula are not inflamed, they often cause no symptoms. However, when acute diverticulitis is present, the main symptom is a sudden, stabbing pain in the lower left abdomen. This pain in the lower left abdomen is often accompanied by fever, bloating, and changes in bowel movements. Nausea or a general feeling of pressure in the lower abdomen are also typical signs. In chronic diverticular disease, recurrent dull abdominal pain may also occur, which can interfere with daily life.

Various factors can increase the risk of diverticular disease. A diet low in fiber is considered the main cause, as it makes stools hard and increases pressure in the intestines. Excessive consumption of red meat, being overweight, and a lack of exercise also contribute to the formation of additional diverticula. In addition, taking certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can increase the risk of diverticular inflammation or bleeding.

If diverticulitis is suspected, a prompt diagnosis is important. In addition to blood tests to measure inflammation markers, a CT scan or ultrasound is the method of choice for visualizing inflamed diverticula. A colonoscopy should not be performed during the acute phase, but it is essential for follow-up care of diverticular disease and to rule out colorectal cancer once the inflammation has subsided. Treatment often consists of a bland diet and, if necessary, antibiotics.

The foundation of any medical diagnosis is the patient interview (medical history). During this process, the doctor asks the patient about

• the nature and severity of the symptoms,
• past medical history,
• medications taken, and
• family medical history.

During the subsequent physical examination, the doctor palpates and auscultates the abdomen. The doctor measures the body temperature and performs a digital rectal exam (examination of the rectum with a finger). A blood test is usually performed as well. In the lab, white blood cell (leukocyte) and CRP levels are checked. CRP stands for C-reactive protein, a marker that typically rises in the presence of inflammation.

Ultrasound and computed tomography (CT) are the primary imaging modalities used. In cases of diverticular disease, there is a risk that the endoscope could perforate (tear) the intestine. Therefore, a colonoscopy should not be performed during the acute phase.

A colonoscopy is performed only in cases of intestinal bleeding from diverticula, in order to locate the source of the bleeding and, if possible, to stop it. If no source of bleeding can be identified, further imaging tests (CT angiography, angiography, or scintigraphy) are necessary.

If mild and nonspecific symptoms persist for more than three to six months, a colonoscopy should be performed. This allows the doctor to definitively rule out other intestinal diseases as the cause.

Not every patient with diverticulitis requires surgery. However, surgery becomes necessary in the event of complications such as an abscess, the formation of a fistula, or following a bowel perforation. Surgery may also be appropriate for people with diverticulosis who suffer from a chronic form of the condition and whose quality of life is severely impaired. In general and visceral surgery today, the affected section of the intestine is usually removed laparoscopically.

People with diverticula should

• engage in regular physical activity,
• maintain or achieve a healthy weight, and
• eat a high-fiber, vegetarian diet. 

These measures can help prevent diverticulitis.

Mild symptoms, such as irregular bowel movements, can often be successfully treated by regulating bowel movements. A high-fiber diet is generally recommended for this purpose.

If a tendency toward constipation persists, additional doses of

• bulking agents (wheat bran, ground flaxseed) as well as
• dairy products (such as plain yogurt)

are recommended. If these measures do not lead to an improvement in symptoms, a doctor (do not self-medicate!) may prescribe laxatives.

Depending on the severity of the condition, treatment ranges from

• regulating bowel movements through a high-fiber diet, to
• antibiotic therapy, and
• surgical removal of sections of the colon containing diverticula, to
• to the control of diverticular bleeding and
• emergency surgery for bowel perforation.

To prevent the development of diverticula or avoid flare-ups, a high-fiber diet is the most important factor. Fiber binds water, softens the stool, and thus reduces pressure in the bowel. Whole-grain products, vegetables, and legumes should be a regular part of a high-fiber diet. Drinking enough fluids and getting regular exercise further support bowel movement and help ensure that people with diverticula remain symptom-free in the long term.

Do diverticula in the colon always need to be treated?

No, as long as the diverticula do not cause any symptoms and only diverticulosis is present, they do not need to be treated. At this stage, a preventive switch to a high-fiber diet is sufficient.

What is the difference between diverticulosis and diverticulitis?

Diverticulosis refers to the mere presence of diverticula. Diverticulitis, on the other hand, refers to an inflammation of these pouches that requires treatment.

What role does meat play in the development of the condition?

A high intake of red meat is often associated with an increased risk of inflammation. A high-fiber diet low in meat helps reduce the risk of diverticular disease.

Can diverticula be removed during a colonoscopy?

Diverticula are outpouchings of the entire intestinal wall and cannot be removed during a colonoscopy, unlike polyps. If they cause problems, surgical removal of the entire affected section of the colon is usually necessary.

Why are older people particularly affected?

Diverticula form over decades due to pressure and a decline in the stability of the intestinal wall. Therefore, older people are significantly more prone to diverticula than young adults.

Does drinking plenty of fluids help with diverticulitis?

During the acute phase, a liquid diet can help relieve pressure on the bowel. For prevention, water is essential so that the dietary fiber you consume can swell in the bowel and keep stools soft.

What happens if a diverticulum ruptures?

A ruptured diverticulum (perforation) is a medical emergency. Intestinal contents and bacteria enter the abdominal cavity, requiring immediate surgical intervention to prevent sepsis.

Where can I find specialists in diverticular surgery?

Specialized clinics for visceral surgery focus on surgical treatment of the large intestine and often offer minimally invasive procedures.