EM@3AM – Diverticulitis

Author: Erica Simon, DO, MHA (@E_M_Simon, EMS Fellow, USAF) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, SAUSHEC, USAF)

Welcome to EM@3AM, an emdocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 56-year-old male, with a history of smoking (20 pack years), presents to the emergency department for one day of left lower quadrant pain and subject fever. He denies nausea, emesis, urinary discomfort, and changes in his bowel movements. He reports a relatively recent colonoscopy, following a previous episode of diverticulitis, as without findings. When questioned regarding his pain, the patient states “…it feels achy, exactly like the last time I had diverticulitis.”

Triage vital signs (VS): BP 137/81, HR 88, T 99.1 Oral, RR 14, SpO2 99% on room air.

What’s the next step in your evaluation and treatment?

Answer: Diverticulitis1-4

  • Etiology: Inflammation and infection of colonic diverticula.
  • Pathogenesis of Diverticular Disease: Current theories emphasize the role of increased intraluminal pressure in the development/progression of diverticular disease:
    • Increased intraluminal pressure => decreased integrity of collagen and elastin in bowel wall muscle tissue => formation of false diverticula. With time, hypertrophy of the circular muscle of the bowel wall => colonic segment shortening and narrowing of distal bowl lumen => propagation of the disease.
    • Pressure across the bowl wall increases as the radius of the wall decreases. The sigmoid colon possesses the smallest radius = most likely area for diverticula development.1
  • Pathogenesis of Diverticulitis:
    • Acute, uncomplicated diverticulitis: colonic diverticula fill with feces => obstruction +/- bacterial overgrowth results in diverticula expansion => compromise of vasculature +/- microperforation => localized infection and inflammation +/- abscess.
    • Complicated diverticulitis: infection/abscess spreads to adjacent viscera => macro-perforation, fistula, bowel obstruction, or large abscess.
  • Epidemiology: In the U.S., the incidence of diverticular disease is reported as > 60% by age 80.1
  • Risk Factors: Smoking, lack of physical activity, and obesity have been associated with diverticulitis. Note: A diet high in fiber has been hypothesized as protective.  Low quality evidencebelieved that stool bulking results in decreased pressure in the colon, which in turn, reduces the risk for the development of diverticular disease.1
  • Clinical Presentation of Diverticulitis: Variable: Patients may present with mild left lower quadrant pain (most common) +/- fever, diarrhea/constipation, or with sepsis, peritonitis, or shock.
  • Evaluation:
    • Assess ABCs and obtain VS.
    • Perform a thorough history and physical exam (H&P).
    • Laboratory studies and imaging as dictated by the H&P:
      • Non-toxic patient with a previous medical history of diverticulitis => see treatment.
      • Individuals with an H&P suggestive of the first episode of acute, uncomplicated diverticulitis:
        • CBC: possible leukocytosis.
        • CT with IV contrast (PO contrast is controversial for additional diagnostic ability) is the diagnostic study of choice (allows for identification of complications, i.e. – fistula, abscess, or colitis).1
      • Toxic appearing patient (SIRS/sepsis) in whom complicated diverticulitis is a concern (25% of all cases of diverticulitis1):
        • CBC may demonstrate leukocytosis. Consider CMP, lactate, and blood cultures (sepsis/shock).
        • If peritoneal signs: acute abdominal series => allows for rapid identification of macro-perforation.
  • Treatment:
    • Acute, uncomplicated diverticulitis in a patient with a history of diverticulitis, or CT-demonstrated first episode of acute, uncomplicated diverticulitis: Consider empiric antibiotic therapy and supportive care with analgesia and stool softeners.
      • Note: Large, randomized controlled trials in both Sweden and the Netherlands have demonstrated antibiotic administration as having no benefit in the setting of acute, uncomplicated diverticulitis:
        • Chabok, et al, 2012: Randomized clinical trial involving 10 surgical departments in Sweden and 1 in Iceland (n=623 patients with CT confirmed, acute, uncomplicated, left-sided diverticulitis): antibiotics neither accelerated recovery, nor prevented complications/recurrence.2
        • Daniels, et al. 2017: Randomized clinical trial including 22 sites in the Netherlands (n = 528 patients with a first episode of CT confirmed, left-sided, acute, uncomplicated diverticulitis): observational treatment alone did not prolong recovery time. No significant differences in terms of progression to complicated diverticulitis, sigmoid resection, or readmission were identified in patients receiving observational treatment vs. oral antibiotic therapy.3
          • If the decision is made to administer antibiotic therapy, consider: (Outpatient 10-14 days):
            • Ciprofloxacin (500 mg oral, three times daily) + Metronidazole (500 mg oral, three times daily)
            • Amoxicillin-Clavulanate (875 mg oral, twice daily)
            • Moxifloxacin (400 mg oral, daily)
    • A toxic patient with radiographic, or CT evidence of complicated diverticulitis: fluid resuscitation as appropriate, parenteral antibiotic therapy, analgesia, and surgery/interventional radiology consultation as applicable.
      • Antibiotics:
        • Piperacillin-tazobactam (3.375 – 4.5 g IV every 6 hours)
        • Imipenem-cilastatin (500 mg IV every 6 hours)
        • Levofloxacin (500 mg IV every 24 hours) + metronidazole (500 mg IV every 8 hours)
        • Ceftriaxone (1 g IV every 24 hours) + metronidazole (500 mg IV every 8 hours)
  •  Disposition:
    • All patients with complicated diverticulitis require admission.
    • Among patients with uncomplicated diverticulitis, consider admission for: the elderly, patients with significant medical co-morbidities, the immunosuppressed, or individuals with a high-grade fever.
    • Non-toxic, well-appearing patients with uncomplicated diverticulitis: discharge to home with follow-up.
  • Pearls:
    • The American Gastroenterological Association suggests that patients with acute diverticulitis be counseled on the importance of a high-fiber diet (low quality evidence).4
    • Colonoscopy is advised for all patients following resolution of acute diverticulitis => exclude colonic neoplasm.1,4
    • Patients ≥ age 50 presenting with their fourth episode of acute diverticulitis should be referred for discussion of definitive surgical management.1



  1. Bope E, Kellerman R. The Digestive System. In Conn’s Current Therapy 2017. Philadelphia, Elsevier. 2017; 4:159-242.
  2. Chabok A, Pahlman L, Hjern F, et al. Randomized clinical trial of antibiotic in acute uncomplicated diverticulitis. Br J Surg. 2012; 99(4):532-539.
  3. Daniels L, Ünlü C, de Korte N, et al. Randomized clinical trial of observational versus antibiotic treatment for a first episode of CT-proven uncomplicated acute diverticulitis. Br J Surg. 2017; 104(1):52-61.
  4. Stollman N, Smalley W, Hirano I. AGA Institute Clinical Guidelines Committee. American Gastroenterological Association Institute guideline on the management of acute diverticulitis. Gastroenterology. 2015; 149(7):1944-1949.


For Additional Reading:

Diverticulitis: Questioning Current Practice

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