Clinical scenario

A 48-year-old man presents to the emergency department (ED) with two days of left lower quadrant pain, fever, and malaise. He has no urinary or bowel symptoms. His past medical history is unremarkable. He is febrile at 38.4 °C, heart rate is 96 beats per minute, blood pressure is 110/98 mmHg and respiratory rate is 18 breaths per minute. After a focussed physical examination, you narrow the differential and consider diverticulitis as the most likely diagnosis. You order analgesia, blood work, intravenous fluids, and a contrast-enhanced computed tomography (CT) scan of his abdomen and pelvis. The report describes acute uncomplicated diverticulitis, and you consider your next steps in management.

  1. 1.

    What is the relevance of defining uncomplicated versus complicated diverticulitis?

Diverticulitis is a commonly seen presentation in the ED whose symptoms range in severity: from mild abdominal discomfort to sepsis. It most commonly affects the descending and sigmoid colon, though right-sided diverticulitis can be seen in some patientsFootnote 1. The distinction between uncomplicated and complicated diverticulitis is defined by the presence of secondary complications. Examples include perforation, abscess formation, strictures, and fistulae. These complications are not reliably elicited on physical examination, therefore, imaging, ideally in the form of a contrast-enhanced CT is necessary to refine the diagnosis [1, 2].

This distinction determines treatment options. The previously accepted pathophysiology of diverticulitis solely as an infectious process has been challenged in recent years. Contemporary literature suggests the process may be inflammatory, rather than infectious [1]. ED physicians should be aware of this changing landscape given that most of these patients are assessed, treated, and then discharged from the ED.

  1. 2.

    What is the evidence for treating uncomplicated diverticulitis without antibiotics?

Two major surgical societies, SAGES (2018) [2] and ASCRS (2020) [1], have released position statements on the management of diverticulitis, underpinned by evidence from randomised controlled trials (RCTs) [3, 4] and systematic reviews [5]. These RCTs demonstrated similar outcomes in patients treated with or without antibiotics for acute uncomplicated diverticulitis. No significant differences between groups were found regarding time to recovery, complications, need for surgical resection, recurrence, readmission, and mortality. A follow-up study [6] 11 years later also failed to demonstrate a difference in recurrence, complication, surgical intervention, or patient-reported quality of life. Those studies also demonstrated antibiotic-related adverse events in those treated with antibiotics. This paradigm shift has been adopted by surgeons worldwide, but has not yet become widespread in the ED. Avoiding unnecessary antibiotic use reduces healthcare expenditure, decreases antibiotic resistance and avoids adverse events such as drug interactions, Clostridium difficile infections, and risks associated with polypharmacy.

  1. 3.

    Who should get antibiotics, and which should I prescribe?

Patients deemed to be high-risk were excluded from those trials. These included pregnant or breastfeeding patients, those with HIV, transplanted organs, renal failure on dialysis, other immunosuppressed groups, and those with recurrent diverticulitis [3]. Other studies reported failure of conservative, non-antibiotic therapy in patients with associated comorbidities, and those with an initial CRP of > 170 mg/L [5]. The ED physician should exercise judgement when considering management options in these patients as they may best be treated with antibiotics and defined follow-up [7]. Guidelines [8] recommend starting broad-spectrum antibiotics against anaerobes and Gram-negative bacteria in patients whose symptoms persist after 48–72 h.

For patients who require antibiotic treatment, there is good-quality evidence to suggest that using amoxicillin–clavulanic acid is as effective as treatment with metronidazole and a fluoroquinolone to reduce risks associated with fluoroquinolones such as C. difficile infection [8]. However, in a patient with a true penicillin allergy, ciprofloxacin and metronidazole is an acceptable choice [8].

  1. 4.

    Which patients require follow-up with a family physician?

There is no clear guidance regarding when and who a patient with uncomplicated diverticulitis should follow up with. Surgical society position statements [1, 2] and family medicine guidelines [7, 8] suggest “patients can continue treatment at home with adequate family and social support and follow up”. It is, therefore, the ED physician’s prerogative to recommend that the patient follows up with their own family physician. Use of antibiotics in patients with acute uncomplicated diverticulitis without a family physician may be considered.

  1. 5.

    When should I involve a surgeon?

Stable patients with acute uncomplicated diverticulitis where the clinician may have concern for malignancy from the history, physical examination, or CT findings should be referred to a surgeon for consideration of colonoscopy [8]. Previously, nearly all patients with diverticulitis received a colonoscopy at 6 weeks after discharge; however, this has since changed, in part due to the increased sensitivity of CT scans. Most patients with acute uncomplicated diverticulitis do not require a routine colonoscopy at any rate more frequent than baseline screening [1, 2].

Patients with complicated diverticulitis require an urgent surgical consultation during that ED visit. In addition, any patient with uncomplicated diverticulitis with haemodynamic instability or refractory to an adequate trial of oral analgesia should also be discussed with the surgeon on call.


Uncomplicated diverticulitis is a commonly encountered condition in the ED. A history and physical examination followed by a CT scan are essential to differentiate between uncomplicated and complicated diverticulitis to help guide further management. Stable patients with uncomplicated diverticulitis with few or no-comorbidities may safely be treated without oral antibiotics upon discharge from the ED. High-risk patients and those with concerning features should be treated with antibiotics. Patients with complicated diverticulitis should be referred to a general surgeon.

Case resolution

The patient was treated with IV fluids and analgesia in the ED. He was not prescribed antibiotics. He tolerated clear fluids and his symptoms resolved in the ED and was successfully discharged home. He was advised to follow up with his family physician in a few days’ time to ensure resolution.

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