Snapshot A 63-year-old female is brought to the emergency room for severe abdominal pain for the past 1 day. She reports that the pain is 9/10, dull, with intermittent exacerbations concentrated at the left lower quadrant (LLQ). She endorses low-grade fever, nausea, and vomiting for the past couple of hours. Her past medical history includes hypertension, constipation, and diverticulosis. A physical examination demonstrates abdominal tenderness and some diffuse voluntary guarding. Introduction Clinical definition gastrointestinal disease characterized by the inflammation of diverticula results from a microscopic or macroscopic perforation of a diverticulum due to diverticular inflammation and focal necrosis patients can present with repeated attacks complicated diverticulitis is defined as diverticulitis with 1 of the following associated complications bowel obstruction abscess fistula perforation Epidemiology Demographics most commonly occurs at the sigmoid colon in North America, reflecting the distribution of diverticulosis right-sided (cecal) diverticulitis is more common in Asian populations approximately 4% of patients with diverticulosis develop acute diverticulitis Risk factors obesity lack of exercise smoking positive family history nonsteroidal anti-inflammatory drugs (NSAIDs) ETIOLOGY Pathogenesis primary process is thought to be due to erosion of the diverticular wall by increased intraluminal pressure or inspissated food particles erosions of the wall then lead to inflammation and focal necrosis that may lead to micro- or macroscopic perforation the inflammation is frequently mild and often walled off by pericolic fat and mesentery this may lead to the formation of a localized abscess or a fistula (if adjacent organs are involved) poor containment of the inflamed diverticulum or abscess can result in free perforation and peritonitis Presentation Symptoms abdominal pain most commonly at the LLQ nausea vomiting constipation diarrhea Physical exam fever hypotension tender mass peritoneal signs (e.g., guarding, rigidity, and rebound tenderness) imaging Computed tomography (CT) with oral and IV contrast best diagnostic test positive findings include localized wall thickening (> 4mm), pericolic fat stranding, and presence of colonic diverticula also allows for visualizations of complications such as abscess, obstruction, or perforation Abdominal ultrasound indicated in patients who cannot receive radiation positive findings include bowel wall thickening, hypoechoic peridiverticular inflammatory reaction, and the presence of diverticula Abdominal and chest radiographs may be useful in detecting pneumoperitoneum and obstruction positive findings include air-fluid levels with bowel dilation or free air Colonoscopy not to be performed during acute diverticulitis for risk of perforation recommended 4-6 weeks after resolution for evaluation and rule out of malignancy Studies Diagnostic testing diagnostic approach diagnosis is based on clinical presentation and is confirmed via imaging studies studies complete blood count may see leukocytosis urinalysis may see sterile pyuria or colonic flora (if colovesical fistula) pregnancy test indicated in all women of childbearing age Differential Inflammatory bowel syndrome (IBD) differentiating factors will often present with more chronic clinical symptoms and will have positive biopsy findings Colorectal cancer differentiating factors will be visualized on colonoscopy Acute appendicitis differentiating factors will appear differently on abdominal CT imaging Treatment Management depends on disease severity, certain characteristics, and the presence of complications the majority of patients with acute diverticulitis can be treated with medical management Outpatient treatment indicated for patients with uncomplicated diverticulitis and no signs of high fever, significant leukocytosis, peritoneal signs, sepsis, immunosuppression, advanced age, intolerance of oral intake, or significant comorbidities oral antibiotics for 7-10 days with following 2-3 days after first visit Inpatient medical management IV antibiotics with transition to oral antibiotics with improvement Gram-negative and anaerobic coverage required IV fluids Parenteral pain medications NPO if unable to tolerate oral intake Surgery indicated for patients with perforated diverticulitis, hemodynamic instability, or peritonitis can be offered electively to patients with recurrent or chronic symptoms, patients who are immunosuppressed or with a prior episode of complicated diverticulitis Complications Abscess should be suspected in patients with uncomplicated diverticulitis showing no improvement despite 3 days of antibiotic treatment if < 3cm, then treat with IV antibiotics if > 3cm, consider CT-guided percutaneous drainge Bowel obstruction Diverticular fistula Perforation Peritonitis Shock