Diverticulitis

Diverticulitis occurs when one or more small pouches (diverticula) in the wall of the colon become inflamed or infected. Diverticula themselves are common with aging and often cause no problems (diverticulosis). When a pouch becomes inflamed, it can cause abdominal pain, fever, and changes in bowel habits.

Mild diverticulitis can often be treated at home with rest, dietary changes, and sometimes antibiotics. Complicated diverticulitis — with abscess, perforation, fistula, or obstruction — may require hospitalization, drainage procedures, or surgery. After recovery, a high-fiber diet and other measures may reduce the risk of recurrent episodes.

Signs and symptoms of diverticulitis can include:

• Persistent pain, most often in the lower left abdomen (right-sided pain is more common in some Asian populations)
• Fever and chills
• Nausea and vomiting
• Abdominal tenderness
• Constipation or, less often, diarrhea
• Bloating and gas
• In severe cases: inability to pass stool or gas, or signs of peritonitis if perforation occurs

Pain that is severe, progressive, or associated with high fever and inability to keep fluids down needs urgent evaluation.

Diverticula form when natural weak spots in the colonic wall give way under pressure, producing marble-sized pouches. Diverticulitis occurs when a pouch becomes inflamed, often with microperforation. The exact trigger is not always clear; stool trapped in a pouch, shifts in the microbiome, and localized ischemia may play roles.

A low-fiber diet, obesity, inactivity, smoking, and certain medicines (NSAIDs, steroids, opioids) are associated with higher risk of diverticular disease and complications.

Risk factors include:

• Age over 40 (risk rises with age)
• Obesity
• Smoking
• Lack of exercise
• Diet high in animal fat and low in fiber
• Certain medications — steroids, opioids, and nonsteroidal anti-inflammatory drugs
• Prior episodes of diverticulitis (risk of recurrence)

Complications can include:

• Abscess
• Perforation and peritonitis
• Fistula formation (to bladder, vagina, or skin)
• Intestinal obstruction or stricture
• Sepsis
• Recurrent attacks that impair quality of life

Measures that may reduce the risk of diverticulitis or recurrence:

• Eat a high-fiber diet rich in fruits, vegetables, whole grains, and legumes
• Drink plenty of fluids
• Exercise regularly
• Maintain a healthy weight
• Do not smoke
• Use NSAIDs only when necessary and at the lowest effective dose
• Discuss the role of mesalamine, rifaximin, or probiotics with a clinician if episodes recur (evidence is mixed)

Nuts, seeds, and popcorn are no longer routinely restricted; evidence does not support avoiding them for most people.

Evaluation may include:

• History and physical examination (including abdominal and sometimes rectal exam)
• Blood tests for infection and inflammation
• CT scan of the abdomen and pelvis — the most useful imaging test to confirm diverticulitis and identify complications
• Ultrasound or MRI in selected situations (e.g., pregnancy)
• Colonoscopy is generally avoided during acute uncomplicated diverticulitis but is often recommended several weeks after recovery to exclude other pathology such as cancer, especially after a first episode

Contact a healthcare professional for constant abdominal pain, especially with fever or change in bowel habits. Seek emergency care for severe pain, high fever, persistent vomiting, dizziness, or a rigid, tender abdomen.

Treatment depends on severity:

Uncomplicated diverticulitis

• Outpatient care for many stable patients: clear liquids advancing to low fiber then regular diet, pain control, and selective use of antibiotics (some mild cases in immunocompetent patients may be managed without antibiotics under guidance)
• Close follow-up to ensure improvement

Complicated or severe disease

• Hospitalization, IV fluids, and IV antibiotics
• Percutaneous drainage of large abscesses
• Surgery for free perforation, persistent obstruction, fistula, failure of medical therapy, or selected recurrent cases — options include resection with primary anastomosis or temporary colostomy depending on contamination and patient stability

Elective resection is individualized for recurrent uncomplicated disease based on frequency, severity, and patient preference.

During recovery and afterward:

• Follow the prescribed diet progression
• Take medicines as directed
• Rest and advance activity gradually
• Return for care if pain, fever, or vomiting worsen
• After recovery, gradually increase fiber and maintain healthy lifestyle habits
• Complete recommended follow-up colonoscopy when advised

Bring:

• Description of pain location, severity, and associated symptoms
• List of medicines (especially NSAIDs, steroids, opioids)
• Prior history of diverticulitis or abdominal imaging
• Questions about need for antibiotics, diet, workup after the acute episode, and prevention of recurrence