Acute Diverticulitis

Shakira Laing

Background

  • Definition: Inflammation and/or infection of a colonic diverticulum.
  • Colonic flora on urine culture or pneumaturia suggests colovesical fistula.

Presentation

  • Lower abdominal pain (85% LLQ), abdominal tenderness, decreased appetite, nausea/vomiting, low-grade fever, change in bowel habits (constipation or diarrhea), leukocytosis.

Evaluation

  • Labs: CBC w/diff, CMP, Lipase, U/A, β-hCG.
  • Imaging: CT abdomen/pelvis with IV contrast (+/- oral contrast).
    • Typical CT findings: localized bowel wall thickening (>4mm), paracolic fat stranding, presence of colonic diverticula.

Management

  • Outpatient management is appropriate for most uncomplicated cases. 
    • Indications for hospitalization: Complicated diverticulitis (abscess, perforation, obstruction, fistula), sepsis, uncontrolled pain, age >70, significant medical comorbidities, immunosuppression, inability to tolerate PO intake.
  • Supportive Care 
    • Diet: Bowel rest vs. clear liquids (advance diet as tolerated).
    • IVF: give IVF for volume depletion in unable to tolerate PO intake.
  • Antibiotics 
    • AGA recommends selective rather than routine use of antibiotics. Reserve for: 
      • Persistent fever or risking leukocytosis.
      • Sepsis/Septic Shock.
      • High risk patients (>70 years old, pregnancy, immunosuppressed, significant comorbidities).
      • CRP >140 or WBC >15 x109 /L.
      • Fluid collection or extensive inflammation on CT scan.
    • Duration: 4-7 days.
    • IV regimen: Zosyn, Cefepime + Metronidazole, or meropenem (if high risk for organisms w/ ESBL).
    • PO regimen: Ciprofloxacin/Levofloxacin + Metronidazole OR Augmentin.
  • Colonoscopy 
    • Recommended after complete resolution of symptoms (6 – 8 weeks) for first case of acute diverticulitis and all cases of complicated diverticulitis.

Complications

  • Patients who fail to improve on IV antibiotics or deteriorate require repeat imaging 
  • Abscess: 
    • < 4cm: IV antibiotics, if fail to improve percutaneous drainage vs surgery 
    • > 4cm: IV antibiotics + percutaneous drainage (if accessible) vs surgery 
  • Obstruction/structuring: Surgical resection needed to relieve obstruction and exclude malignancy (difficult to differentiate from cancer radiographically) 
  • Fistula: Most commonly colovesical, colovaginl, coloenteric, or colouterine. Rarely heal spontaneously, surgical correction typically required. 
  • Diverticular bleeding: most common cause of overt lower GI bleeding in adults, typically resolves spontaneously. If persistent, 
    • HDS: Colonoscopy to locate and treat 
    • HDUS: Angiography for localization/embolization 
    • Refractory bleeding: Segmental colectomy if bleeding site identified, subtotal colectomy if site unknown 
    • Surgical management for a diverticular bleed is rare and should be a last resort approach. 
  • Perforation 
    • Microperforation (contained perforation): Presence of small amount of air bubbles, without oral contrast extravasation. Treat with IV abx and bowel rest. 
    • Frank perforation (free perforation): Intraabdominal free air, air under the diaphragm, and diffuse peritonitis requires emergency surgery so consult EG 
  • Recurrent diverticulitis 
    • Elective surgery generally not recommended for patients with prior diverticulitis episodes if they were managed medically and uncomplicated. 
    • Indications for elective surgery include: 
      • Prior episode of complicated diverticulitis 
      • Immunosuppressed patients 
      • Surgery typically performed 10-12 weeks after last acute diverticulitis episode 
  • Segmental colitis associated with diverticulosis (SCAD) 
    • Definition: chronic mucosal inflammation in a segment of colon with diverticula 
    • Pathogenesis: currently unknown, leading hypotheses include fecal stasis, localized ischemia, and mucosal prolapse 
    • Symptoms: chronic diarrhea, abdominal pain, intermittent hematochezia 
    • Diagnosis: colonoscopy with chronic inflammatory changes on biopsy only in an area of the colon with diverticula (sigmoid colon>>descending colon) and absence of inflammation in the rectum (compared to ulcerative colitis, which always involves the rectum) 
    • Rule out other causes: acute uncomplicated diverticulitis (increased paracolic fat stranding/mild colonic wall inflammation, endoscopy shows primary involvement of diverticular orifices and peri diverticular mucosa), infectious colitis (stool studies/tissue biopsy), NSAID-induced colitis (medication exposure), ischemic colitis (acute presentation), IBD (UC involves rectum, CD typically involves other sites in GI tract), radiation colitis (history of radiation, tissue biopsy showing eosinophils) 
    • Management: Start with antibiotics (cipro or flagyl x 10-14 days), if unresponsive, add oral mesalamine x 7-10 days with dose escalation if persistent after 2 weeks. If symptoms remain, start prednisone 40 mg and gradually taper over 6 weeks.
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