What is Diverticulitis

Diverticulitis occurs when small pouches (diverticula) in the colon wall become inflamed or infected. In Western countries, most diverticula occur in the sigmoid and descending colon, while in Asian populations the ascending colon is more commonly affected. Uncomplicated diverticulitis involves localized inflammation; complicated diverticulitis includes abscess, phlegmon, fistula, obstruction, bleeding, or perforation.

Causes and Risk Factors

Diverticulitis is triggered by a tear in a diverticulum, allowing bacteria or stool to infect the pouch. Risk factors include:

  • Diet: Low‑fiber, Western‑style diets increase risk; a high‑fiber diet rich in fruits, vegetables, whole grains, and legumes may reduce risk. Nuts, corn, popcorn, and seeds are not associated with an increased risk.
  • Physical inactivity: Regular exercise, particularly vigorous activity, appears protective.
  • Obesity: Central obesity and weight gain increase risk.
  • Smoking and alcoholism: Both are associated with higher risk.
  • Medications: Routine use of non‑steroidal anti‑inflammatory drugs (NSAIDs) and opiates increases risk; aspirin and other NSAIDs modestly increase risk.
  • Genetics and age: Twin studies suggest a strong genetic component. Diverticulosis becomes more common with age; fewer than 5 % of individuals with diverticulosis develop diverticulitis.

Symptoms of Diverticulitis

Symptoms often begin suddenly and can range from mild to severe:

  • Left lower quadrant abdominal pain or cramping (upper right pain may occur in some Asian patients)
  • Abdominal distension or tenderness
  • Fever and chills
  • Nausea or vomiting
  • Constipation or diarrhea
  • Anorexia or loss of appetite
  • Dysuria (painful urination)
  • Rectal bleeding (in complicated cases)

Diagnosis

Diagnosis includes clinical evaluation and imaging. Laboratory tests (complete blood count, metabolic panel, urinalysis, C‑reactive protein) assess severity. A contrast‑enhanced CT scan of the abdomen and pelvis is the preferred method to confirm diverticulitis and look for complications. Ultrasound or MRI may be used when CT is contraindicated, but plain radiographs are only useful for detecting perforation or obstruction. Colonoscopy is avoided during an acute episode due to perforation risk, but is advised 6–8 weeks after recovery, particularly after a first episode of uncomplicated diverticulitis or any episode of complicated diverticulitis, unless a recent high‑quality colonoscopy has been performed.

Treatment

Management depends on disease severity and patient factors:

  • Uncomplicated diverticulitis: Many immunocompetent patients can be managed at home on a clear‑liquid diet with close follow‑up; antibiotics are used selectively because evidence shows they do not speed recovery or prevent complications.
  • Hospital care: Indicated for signs of peritonitis, severe symptoms, immunosuppression, or inability to tolerate oral intake. Treatment includes intravenous fluids, antibiotics, bowel rest, and sometimes nasogastric decompression. CT‑guided percutaneous drainage is used for localized abscesses.
  • Surgery: Reserved for complications such as perforation, obstruction, fistula, or uncontrolled sepsis, or for recurrent disease causing persistent symptoms. Laparoscopic surgery generally results in shorter hospital stay and fewer complications than open surgery. Elective colon resection should be individualized and not based solely on the number of episodes.

Recurrence and Prognosis

Approximately 20 % of patients experience at least one recurrence of diverticulitis, with around 8 % recurring within one year. Recurrence risk increases with each episode: about 18 % at one year and 55 % at ten years after a second episode, and around 40 % at three years after a third episode. Only about 12 % of patients present with complicated disease. Most people recover completely with appropriate care, but recurrence is more likely after complicated diverticulitis.

Prevention and Lifestyle Recommendations

To lower the risk of diverticulitis and prevent recurrences:

  • Eat a high‑fiber diet with plenty of fruits, vegetables, whole grains, and legumes. There is no evidence that nuts, corn, popcorn, or fruits with small seeds trigger diverticulitis.
  • Maintain a healthy weight and avoid central obesity.
  • Engage in regular physical activity.
  • Stop smoking and limit alcohol consumption.
  • Avoid long‑term use of NSAIDs (except low‑dose aspirin for cardiovascular disease) and review medications with your healthcare provider.
  • Stay well hydrated and consider fiber supplements if dietary fiber is insufficient.
  • Manage chronic conditions and discuss family history of diverticular disease with your doctor.

When to Seek Medical Attention

Seek immediate medical care if you experience persistent or severe abdominal pain, fever, chills, vomiting, rectal bleeding, or if you cannot tolerate fluids. Early evaluation helps prevent complications.

References

  1. Peery AF, Shaukat A, Strate LL, et al. AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis: Expert Review. Gastroenterology. 2020;160:906–911.e1. doi:10.1053/j.gastro.2020.09.059
  2. Wilkins T, Embry K, George R. Diagnosis and Management of Acute Diverticulitis. American Family Physician. 2013;87(9):612–620.
  3. Cleveland Clinic. Diverticulitis: Symptoms, Causes & Treatment. Updated 2024.
  4. Strate LL, Morris AM. Epidemiology, Pathophysiology, and Treatment of Diverticulitis. Gastroenterology. 2019;156:1282–1298.e1. doi:10.1053/j.gastro.2018.12.033
  5. American College of Physicians. ACP guidelines on the diagnosis and management of diverticulitis. 2024.