What Is the Main Cause of Diverticulosis?

A high-fat, low-fiber diet is the main culprit in diverticulosis, or the formation and periodic inflammation of out-pouchings in the intestinal wall. Genetics and low physical activity levels may also play a role.

Diverticulosis is a form of diverticular disease, which occurs when small pouches in the large intestinal (colonic) wall called diverticula arise and push through weak spots in the colon’s outer muscle layers. Diverticular disease that is not inflamed is called diverticulosis. Inflammation of the diverticula is called diverticulitis.

Most of the time, diverticulosis does not cause symptoms. When symptoms of diverticulosis occur, they may include:

• Bloating
• Constipation 
• Diarrhea
• Lower abdominal pain or cramping 

See a doctor if you have symptoms of diverticular bleeding, such as: 

• A large amount of red or maroon-colored blood in the stool
• Dizziness 
• Lightheadedness
• Weakness

If the diverticula become inflamed, it becomes diverticulitis. Symptoms of diverticulitis include:

• Pain in the lower left side of the abdomen
  • Is usually severe 
  • Comes on suddenly
  • May also be mild and worsen over several days
  • Intensity of the pain can change over time
• Constipation 
• Diarrhea
• Fever
• Chills
• Nausea
• Vomiting

The main cause of diverticulosis in Western countries is thought to be due to a high-fat and low-fiber diet. 

Other possible causes of diverticulosis include: 

• Straining to have a bowel movement from constipation 
• Genetics
• Obesity
• Lack of exercise
• Smoking
• Use of certain medications including nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, and steroids

Diverticulosis is diagnosed with a physical examination and patient history, along with tests such as: 

• Blood tests
  • White blood cell count 
  • Hemoglobin level 
  • Electrolyte assays 
  • Blood cultures 
  • Renal function tests
  • Liver enzyme and lipase levels 
• Urine tests
  • Urinalysis 
  • Urine culture 
• Stool test for blood
• A pregnancy test for females of childbearing age with abdominal pain
• Imaging tests
  • Computed tomography (CT) scanning of the abdomen 
  • Lower GI series (barium contrast enema, using water-soluble medium)
  • Abdominal radiographic (X-ray) series
  • Colonoscopy

Treatment for diverticulosis is focused on preventing the pouches from becoming inflamed and causing symptoms.

Treatment for diverticulosis may include:

• High-fiber diet
• Fiber supplements
• Medicines
  • Mesalazine (Asacol) 
  • Rifaximin (Xifaxan) 
• Probiotics

Diverticular bleeding is rare but can be severe. Treatment for diverticular bleeding may include: 

• Colonoscopy to find the bleeding and stop it
• Computerized tomography (CT) scan or an angiogram to find the bleeding site
• Colon resection surgery in severe cases

If the diverticula become inflamed and diverticulitis occurs, treatment for mild diverticulitis may include: 

• Clear liquid diet for 2-3 days; progressing to a soft diet as tolerated
• 7-10 days of oral broad-spectrum antibiotics if needed, such as:
  • Ciprofloxacin (Cipro) plus metronidazole (Flagyl)
  • Trimethoprim-sulfamethoxazole (Bactrim) plus metronidazole (Flagyl)
  • Amoxicillin-clavulanate (Augmentin) 
  • Moxifloxacin (Avelox) (for patients intolerant of both metronidazole and beta-lactam agents)
• Acetaminophen (Tylenol) and antispasmodics for pain

Complications of diverticulosis (if it becomes inflamed and diverticulitis occurs) may include:

• Abscess (most common complication)
• Intestinal perforation
• Generalized peritonitis (inflammation of the tissue that lines the wall of the abdomen)
• Intestinal fistula
• Intestinal obstruction
• Stricture of colon
• Sepsis (can be life-threatening)

The primary way to prevent diverticulosis is with proper diet and exercise. Diverticular disease can be due to a low fiber diet, so consumption of a high fiber diet with plenty of vegetables and fruits, whole grains, and other high fiber foods is the mainstay of prevention.