Home Intra-abdominal infections Acute left colonic diverticulitis

Acute left colonic diverticulitis


Acute left colonic diverticulitis (ALCD) is a common problem encountered by surgeons in the acute setting. It encompasses a variety of conditions, ranging from localized diverticular inflammation to perforation and fecal peritonitis. Daily decisions in the diagnosis and treatment of acute diverticulitis often depend on clinicians’ personal preferences rather than evidence-based medicine.


ALCD ranges in severity from uncomplicated inflammatory diverticulitis to complicated diverticulitis (abscess formation or perforation). For the past three decades, the Hinchey classification has been the most commonly used classification for complicated ALCD in international literature.

Based on the surgical findings of abscesses and peritonitis, Hinchey classified the severity of acute diverticulitis into four grades:

  • Stage 1 Pericolic abscess
  • Stage 2 Pelvic, intra-abdominal, or retroperitoneal abscess
  • Stage 3 Generalized purulent peritonitis
  • Stage 4 Generalized fecal peritonitis

The management of ALCD has recently changed dramatically in recent years, due to better radiological imaging and availability of non-surgical treatment options. Computer tomography (CT) imaging has become a primary diagnostic tool in the diagnosis and staging of patients with acute diverticulitis and more detailed information provided by CT scans led to several modifications of the Hinchey classification.

In 2002 Ambrosetti et al. classified diverticulitis into severe or moderate disease. In this classification, the CT scan determined the grade of severity guiding the physician in the treatment of acute complications. Moderate diverticulitis was defined by wall thickening of ≥ 5 mm and signs of inflammation of pericolic fat. Severe diverticulitis was defined by wall thickening accompanied by abscess formation, extraluminal air or extraluminal contrast leak:

Moderate diverticulitis

  • Localized sigmoid wall thickening
  • Pericolic fat stranding

Severe diverticulitis

  • Abscess
  • Extraluminal air
  • Extraluminal contrast

In 2005 Kaiser et al. modified Hinchey classification according to specific CT findings:

  • Stage 0 mild clinical diverticulitis
  • Stage 1a confined pericolic inflammation,
  • Stage 1b confined pericolic abscess
  • Stage 2 pelvic or distant intra-abdominal abscess
  • Stage 3 generalized purulent peritonitis
  • Stage 4 fecal peritonitis at presentation.

In 2015 Sallinen at al. published an interesting retrospective study of patients treated for diverticulitis, setting the stage for the treatment of acute diverticulitis based on clinical, radiologic and physiologic parameters. They included 5 stages:

  • Stage 1 Uncomplicated diverticulitis
  • Stage 2 Complicated diverticulitis with small abscess (<6 cm)
  • Stage 3 Complicated diverticulitis with large abscess (≥6 cm) or distant intraperitoneal or retroperitoneal air
  • Stage 4 Generalized peritonitis without organ dysfunction
  • Stage 5 Generalized peritonitis with organ dysfunction

A proposal for a CT guided classification of left colon acute diverticulitis was published in 2015 by the WSES acute diverticulitis working group. It is a simple classification system of acute diverticulitis based on CT scan findings. It may guide clinicians in the management of acute diverticulitis and may be universally accepted for day to day practice. The WSES classification divides acute diverticulitis into 2 groups: uncomplicated and complicated.In the event of uncomplicated acute diverticulitis, the infection does not extend to the peritoneum. In the event of complicated acute diverticulitis, the infectious process proceeds beyond the colon. Complicated acute diverticulitis is divided into 4 stages, based on the extension of the infectious process:


  • Stage 0. Diverticula, thickening of the colonic wall or increased density of the pericolic fat


  • Stage 1a Pericolic air bubbles or little pericolic fluid without abscess (within 5 cm from inflamed bowel segment)
  • Stage 1b Abscess ≤ 4 cm
  • Stage 2a Abscess > 4 cm
  • Stage 2b Distant air (>5 cm from inflamed bowel segment)
  • Stage 3 Diffuse fluid without distant free air (no hole in colon)
  • Stage 4 Diffuse fluid with distant free air (persistent hole in colon)


Clinical signs and symptoms

  • Abdominal pain in the lower left quadrant of the abdomen without vomiting
  • Elevated temperature
  • Abdominal tenderness (sign of complicated acute diverticulitis)

Laboratory markers

  • White blood cell
  • Leucocyte shift to left (>75 %)
  • C-reactive protein


  • US
  • CT

Imaging findings

  • Intestinal wall thickening
  • Signs of inflammation in the pericolonic fat and thickening of the lateroconal fascia
  • Signs of intestinal perforation (extraluminal gas, intra-abdominal fluid)
  • Pericolonic or distant abscess
  • Fistulas with adjacent organs
CT imaging is becoming by now the gold standard in the diagnosis and staging of patients. CT imaging with intravenous contrast has excellent sensitivity and specificity. US is a real-time dynamic examination with wide availability and easy accessibility and may be useful in diagnosing and managing critically ill patients who cannot be moved to CT. Its limitations include operator-dependency, poor assessment in obese patients, difficulty in the detection of free air and deeply located abscesses.
A step-up approach with CT performed after an inconclusive or negative US, has been proposed as safe and alternative approach.


Uncomplicated diverticulitis

  • – Antibiotic therapy for 5-7 days.
  • – Conservative treatment without antibiotics in selected patients (CT diagnosis of uncomplicate acute diverticulitis, no signs of inflammatory response).

Outpatient management is suggested for patients with uncomplicated acute diverticulitis, with no comorbidities. These patients should be clinically monitored as outpatients and re-evaluated within 7 days to assess for resolution of the inflammatory processes. Earlier revaluation is necessary if the clinical condition deteriorates.

Abdominal abscess

  • – Antibiotic therapy alone for 5-7 days in patients with small diverticular abscesses.
  • – Percutaneous drainage combined with antibiotic therapy for 3-5 days in large diverticular abscesses.

Whenever percutaneous drainage of the abscess is not feasible or not available, based on the clinical conditions patients with large abscesses can be initially treated by antibiotic therapy alone. However careful clinical monitoring is mandatory.

Diffuse peritonitis

  • – Primary resection with anastomosis with or without a diverting stoma (in clinically stable patients with no co-morbidities)
  • – Hartmann resection (in critically ill patients and/or in patients with multiple comorbidities).
  • – Laparoscopic peritoneal lavage and drainage. Very debated. Anyway never in patients with generalized peritonitis
  • +
  • Antibiotic therapy for 3-5 days

Patients who have ongoing signs of infection or systemic illness (ongoing infection) beyond 5 to 7 days of antibiotic treatment, should warrant a diagnostic investigation.
Hartmann’s procedure has been considered the procedure of choice in patients with generalized peritonitis and remains a safe technique for emergency colectomy in diverticular peritonitis, especially in critically ill patients and in patients with multiple co-morbidities. However, restoration of bowel continuity after Hartmann’s procedure has been associated with significant morbidity.
In recent years, some authors have reported the role of primary resection and anastomosis with or without a diverting stoma, in the treatment of diverticulitis, even in the presence of diffuse peritonitis. The decision regarding the surgical choice in patients with diffuse peritonitis is generally left to the judgment of the surgeon, who takes into account the clinical condition and the comorbidities of the patient.
A conservative approach using laparoscopic peritoneal lavage and drainage has been debated in recent years as an alternative to colonic resection. It can potentially avoid a stoma in patients with diffuse peritonitis. Great debate is still open on this topic, mainly due to the discrepancy and sometime disappointing results of the latest prospective trials.

Empiric antibiotic regimens. Normal renal function

  • One of following antibiotics
  • Amoxicillin/clavulanate 1.2-2.2 g 8-hourly
  • Piperacillin/Tazobactam 4.5 g 6-hourly (critically ill patients)
  • Ceftriaxone 2 g 24-hourly + Metronidazole 500 mg 6-hourly
  • or
  • In patients with beta-lactam allergy
  • A fluoroquinolone-based regimen
  • Ciprofloxacin 400 mg 8/12-hourly + Metronidazole 500 mg 6- hourly
  • or
  • In patients at high risk for infection with community-acquired ESBL-producing Enterobacteriaceae
  • One of the following antibiotics
  • Tigecycline 100 mg LD, then 50 mg 12-hourly (Carbapenem-sparing strategy)
  • Ertapenem 1 g 24-hourly
  • Meropenem 1 g 8-hourly (only in patients with septic shock)
  • Doripenem 500 mg 8-hourly (only in patients with septic shock)
  • Imipenem/Cilastatin 500 mg 6-hourly (only in patients with septic shock)

In patients at high risk for infection with Enterococci including immunocompromised patients or patients with recent antibiotic exposure consider use of Ampicillin 2 g 6-hourly if the patients are not being treated with Piperacillin/Tazobactam or Imipenem/Cilastatin (active against ampicillin-susceptible enterococci) or Tigecycline.