Diverticulitis can range from mild to very serious. Mild cases often respond well to outpatient treatment with antibiotics and rest. However, in more severe cases, diverticulitis can lead to serious complications such as abscess formation, perforation (rupture) of the bowel, peritonitis (life-threatening infection of the abdominal cavity), bowel obstruction, or fistulas (abnormal connections to other organs). Severe diverticulitis typically requires hospitalization and sometimes surgery. Immediate medical attention is needed if symptoms include severe abdominal pain, high fever, persistent vomiting, inability to pass stool or gas, or signs of sepsis. Early diagnosis and treatment are important to prevent progression and complications.