Diverticulitis (also called colonic diverticulitis) occurs when small bulging pouches called diverticula in the wall of your large intestine become inflamed or infected.

What's the Difference Between Diverticulosis and Diverticulitis?

According to the National Institutes of Health, diverticulosis is a type of diverticular disease that occurs when small pouches (diverticula) form in the intestinal wall. It is widespread, affecting an estimated 1 out of 10 people over 40 in the United States (1, 1a), and usually does not cause any symptoms.

Diverticulitis is an infection of those small pouches that can lead to severe complications if left untreated. It is the most serious type of diverticular disease.

According to the International Foundation for Gastrointestinal Disorders, "Diverticulosis leads to diverticulitis in about 1 out of 5 to 1 out of 7 cases." (2)

Symptoms of Diverticulosis

Most people with diverticulosis don't experience symptoms. This is called asymptomatic diverticulosis. Consequently, they are often unaware they have this condition. However, when several diverticula are present, it can disrupt normal bowel function. This can cause a variety of symptoms, including:

• Constipation
• Diarrhea
• Changing bowel habits, possibly alternating between constipation and diarrhea
• Gas (flatulence)
• Bloating
• Blood in the stool
• Anemia from blood loss, if it occurs often
• Occasional pain in the lower left side of the abdomen, usually after eating or passing stools.

Symptoms of Diverticulitis

Symptoms of diverticulitis may include:

• Abdominal pain, especially in the lower left half of the abdomen. This pain may be constant and last for several days
• Constipation
• Abdominal tenderness
• Nausea
• Vomiting
• Fever
• Chills
• Cramps in the lower abdomen
• Abdominal bloating
• Painful and/or more frequent urination
• Blood in the stool
• Rectal bleeding

Diverticulosis and Diverticulitis Risk Factors

Low-Fiber Diet

A low-fiber diet and constipation have been considered the most significant risk factor for diverticulitis since the 1960s. Without adequate fiber intake, you must push harder to expel waste, which increases the risk of fecal matter getting stuck in the diverticula and causing infection.

But recent studies do not show an association between low-fiber diets/constipation and increased diverticulitis risk (3,4). However, fiber may undoubtedly play a role. For example, one study found that at least half of the cases of diverticulitis could be prevented by following a healthy lifestyle that includes consuming more than 23 grams of fiber per day.

Infographic Text:

Changes of structural properties of dietary fiber during digestion.
Mouth: no significant changes
Stomach: products of acid hydrolysis
Small intestine: ileum microbiota fermentation
Large intestine: microflora fermentation metabolites
Nonfermentable dietary fiber scraps (with an image of a downward pointing arrow signifying excretion.)

End Infographic Text

Age

The diverticulosis and diverticulitis risk increase with age.

The International Foundation for Gastrointestinal Disorders states that "about 1 out of 10 people over age 40, half of those older than 60, and 2 out of 3 over 80 have [diverticulosis]. (5)

The prevalence of diverticular disease is 65% in those 65 years and older. (6)

Obesity

Being significantly overweight (obese) is thought to increase the risk of developing this disease. However, research suggests that the location of body fat is more important than overall weight for increasing the risk.

In a population-based study published in Mayo Clinic Proceedings, researchers noted: "Rather than BMI per se, increased abdominal visceral and subcutaneous fat are independently associated with diverticulitis. " (8)

Lack of Exercise

We've long known that regular exercise has many health benefits. Now researchers have discovered that it may even reduce diverticulitis risk.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, exercise decreases the risk of diverticula formation. It also stimulates intestinal activity, thus improving digestive function. (9)

And research suggests that exercise combined with weight control can be a protective factor against diverticulitis. In a February 2012 study published in the ​American Journal of Gastroenterology, researchers found that adult females who were overweight and exercised less than 30 minutes a day had a significantly higher risk of developing diverticular disease than those who were of "normal" weight and exercised more frequently. (10)

Smoking

There is a link between cigarette smoking and diverticulitis.

After conducting a comprehensive meta-analysis of 3 studies involving 130,520 participants comparing the risk of colonic diverticulosis among current and former smokers versus nonsmokers, researchers concluded: "A significantly increased risk of colonic diverticulosis among current smokers is demonstrated in this study." (11)

It is not clear why cigarette smoking increases the risk of diverticular disease.

Alterations in the Gut Microbiome

Alterations in the gut microbiome have been observed in those developing acute diverticulitis. Specifically, there was a decrease in anti-inflammatory bacterial species, leading to intestinal inflammation. (12)

Researchers have also observed bacterial colonization of diverticula involved in the development of acute diverticulitis. (13)

Certain Medications

Specific medications are associated with an increased risk of diverticulitis, including:

• Steroids
• Opioids
• Nonsteroidal anti-inflammatory drugs, such as Advil, Aleve, and Motrin IB

Complications of Diverticulitis

Around 25% of diverticulitis cases develop serious complications (complicated diverticulitis) and must be aggressively treated. (14)

The most common diverticulitis complications include:

• Diverticular Abscess. A diverticular abscess is an infected diverticulum filled with pus. It is confined to a specific area of infection.
• Phlegmon. A phlegmon is similar to an abscess, except it's not confined to a specific area and can spread.
• Gastrointestinal Fistula. A gastrointestinal fistula is an abnormal passage that develops between the bowel and a nearby organ.
• Intestinal perforation. Intestinal perforation is a tear in the intestinal wall causing the colon's contents to leak into the abdominal cavity. This can cause inflammation and infection that can be life-threatening if not treated promptly.
• Intestinal obstruction. Intestinal obstruction is a blockage in your intestine that prevents stool from passing and can be deadly.

How is Diverticulitis Diagnosed?

If you have asymptomatic diverticulitis, meaning that you are not exhibiting any symptoms, your healthcare provider will probably discover diverticulitis, diverticulosis, or diverticular disease while examining you for other digestive system conditions, such as colorectal cancer. Diverticulitis is often specifically diagnosed when you're having severe symptoms called an acute attack.

To diagnose diverticulitis and diverticular disease, your doctor may perform or order some of the following tests:

• Medical history. Your healthcare provider will ask you about your medical history, including all your medications. They will also ask about your dietary habits.
• Symptom Inventory. Your doctor will also take an inventory of your symptoms to see if they are consistent with diverticular disease.
• Physical exam. Your healthcare provider will manually and visually inspect your body for signs of diverticulitis, such as abdominal tenderness and distension. This inspection will usually include a digital rectal exam.
• Colonoscopy. This test looks for abnormalities in the colon wall and rectum, such as polyps, colorectal cancer, and irritated or inflamed tissue.
• CT scan. This scan uses x-rays to create cross-sectional images. It can spot abscesses that are outside of the bowel lining. A CT scan is considered the best imaging method to confirm a diverticulitis diagnosis. (15)
• Blood tests. Testing the blood is crucial to detect infection.
• Urinalysis. This test checks for signs of infection and can often indicate the location of diverticulitis.
• Barium enema. This enema uses a contrasting dye to take clear images of the bowel and anus.
• Stool tests. A thorough exam of your stool is conducted to see if there is any blood in the feces or the presence of infection.

Conditions that Mimic Diverticulitis

Because you can develop diverticulitis anywhere along the gastrointestinal tract, symptoms may mimic several other conditions, including:

• Urinary tract infection
• Small bowel obstruction
• Acute appendicitis, if the pain is on the lower right side of the abdomen
• Peptic ulcer disease
• Pancreatitis, inflammation of the pancreas
• Cholecystitis, inflammation of the gallbladder
• Irritable bowel disease
• Crohn's disease
• A gynecological issue, such as ovarian cystic disease

Diverticulosis and Diverticulitis Treatment Options

According to the National Institute of Diabetes and Digestive and Kidney Disease, "Your doctor will recommend diverticular disease treatments based on whether you have chronic symptoms, diverticulitis, or complications." (16)

Here are some of the most common treatments your doctor may recommend for diverticulosis and diverticulitis.

Diverticulosis Treatments

High Fiber Diet

Gradually increasing soluble fiber intake will help improve digestive issues and reduce mild diverticulitis symptoms.