diverticulitis

Etiology

• microperforation with inflammation of a diverticulum
• risk factors
  • aspirin & NSAIDS increase risk of diverticulitis
  • red meat intake increases risk of diverticulitis
    • 18% increase in risk with each daily serving

Epidemiology

• more common in women

Pathology

• microperforation of diverticula
• diverticula become blocked, trap colonic bacteria, & subsequently become inflamed
  • obstruction at the diverticular neck by fecal matter
  • mucus accumulation
  • bacterial overgrowth
  • inflammation.

Clinical manifestations

• abdominal pain & tenderness
  • may be crampy initially (colic), but becomes constant in nature
  • generally left lower quadrant pain
  • onset is frequently gradual
  • 'acute' abdomen is uncommon
    • secondary to peritonitis
    • abdominal guarding & rebound tenderness
    • may represent frank perforation
    • surgical emergency
  • relief with flatus or bowel movment
• fever > 38 C (may be < 38 C in uncomplicated cases)
• changes of bowel habits
  • constipation (most common)
  • diarrhea (less frequently)
  • ref suggests diarrhea more common
• nausea/vomiting
  • localized inflammation/edema-induced obstruction
  • abscess causing obstruction
  • spasm
  • sepsis
  • electrolyte abnormalities
• malaise
• urinary complaints
  • dysuria/frequency secondary to adjacent bladder inflammation
  • pneumaturia secondary to colovesical fistula
• hypoactive bowel sounds, ileus
• occult fecal blood to bright red blood per rectum
  • may present as recurrent BRBPR without abdominal pain
  • MKSAP19 states acute diverticulitis does not present with rectal bleeding
• abdominal mass if significant abscess or inflammation

Laboratory

• complete blood count (CBC) with differential
  • leukocytosis with left shift
• elevated inflammatory markers
  • erythrocyte sedimentation rate (ESR) is generally elevated
  • elevated serum C-reactive protein
  • elevated serum procalcitonin
• urinalysis for evidence of colovesical fistula
  • hematuria
  • pyuria

Diagnostic procedures

• flexible sigmoidoscopy, colonoscopy
  • of limited value, except in cases of complicated left-sided diverticulitis
    • colorectal cancer can masquerade as left-sided diverticulitis
  • avoid in the acute setting
    • wait minimum of 6-8 weeks after resolution of symptoms
  • risk of insufflation-induced intestinal perforation
  • colonoscopy 1-2 months after recovery to rule out colon cancer
    • see Follow-up in Management section

Radiology

• imaging
  • unnecessary if clinical features highly suggestive of diverticulitis
  • helpful with predictive value
    • failure of medical treatment
    • development of complications
• computed tomography (CT) of abdomen & pelvis
  • imaging modality of choice
    • low radiation dose without contrast
  • indications:
    • diagnosis & guidance of therapy
    • severe pain, high fever, palpable mass
  • features
    • sigmoid diverticula with focal bowel wall thickening
    • inflammation of the pericolic fat.
    • diverticular pericolic abscess vs non-diverticular etiology of abdominal pain
  • procedure: CT-guided drainage of larger abscesses
• plain abdominal radiograph
  • signs of obstruction
    • distended bowel loops with abrupt termination
    • air/fluid interfaces
  • signs of perforated viscus (rare)
    • free air under the diaphragm
  • ileus (common)
  • extracolonic gas pattern suggestive of pericolic abscess
• barium enema with water-soluble contrast
  • poor yield of extracolonic pathology
• abdominal ultrasound
  • generally less useful than CT or barium enema

Complications

• fistula to bladder (enterovesical fistula), vagina or skin
  • enterovesical
• pericolic abscess:
  • if < 2 cm, medical management
  • CT-guided drain placement for pericolic abscesses >= 4 cm in diameter & nonresolving pericolic abscess
• bowel perforation & peritonitis: surgery
• bowel obstruction: surgery
• most chronic symptoms likely related to visceral hypersensitivity

Differential diagnosis

• intestinal ischemia (ischemic colitis)
  • patient generally with diffuse atherosclerotic disease
  • abdominal pain & tenderness over affected region
  • BRBPR ischemic colitis
  • hypotension, use of vasopressor suggests ischmemic colitis
• colorectal cancer
• intestinal obstruction
• appendicitis
• duodenal ulcer
• inflammatory bowel disease
• tubo-ovarian abscess:
  • generally younger, sexually-active women
• sigmoid volvulus
• pancreatitis
• diverticular bleeding (without diverticulitis) is painless
• pyelonephritis
• urolithiasis

Management

• indications for hospital admission
  • evidence of obstruction
  • unable to tolerate liquid diet
  • significant fever
  • leukocytosis (WBC > 12,000/mm3)
  • severe abdominal pain & tenderness
  • immunosuppression
  • failure to improve after 24-36 hours
  • uncomplicated diverticulitis may be treated as outpatient even in elderly with comorbidities
• nasogastric tube (NGT) for decompression if distended
• pharmacologic agents
  • avoid antibiotics in otherwise healthy adults with early diverticulitis
  • antibiotic coverage
    • E coli, Bacteroides fragilis, anaerobes
    • 7-10 days of therapy
  • mild cases/outpatient
    • ciprofloxacin 500 mg PO BID + metronidazole 500 mg PO BID
    • tetracycline or Bactrim plus metronidazole
    • amoxicillin/clavulanate
    • antibiotics do not improve outcomes
      • antibiotics not routinely required in immunocompetent patients
    • higher risk of C difficile colitis with quinolone vs amoxicillin/clavulanate in elderly
  • hospitalized patients
    • ciprofloxacin 500 mg PO BID plus metronidazole 500 mg PO BID even in ICU patient unless unable to tolerate oral diet (persistent vomiting)
    • intravenous antibiotics
      • ceftriaxone + metronidazole
      • ampicillin + aminoglycoside + metronidazole
      • ampicillin sulbactam (Unasyn)
      • ticarcillin clavulanate (Timentin)
      • piperacillin tazobactam (Zosyn)
      • Imipenem cilastatin (Primaxin)
    • transition to oral antibiotics when food is tolerated
  • limitations of antibiotics
    • antibiotics may not improve outcomes
    • antibiotics do not reduce pain, complictions requiring surgery, readmission or length of hospitalization in uncomplicated diverticulitis
  • indications for antibiotics in uncomplicated cases
    • comorbidities
    • immunosuppression
    • serum C-reactive protein > 140 mg/L
    • WBC count > 15,000/uL
    • presence of fluid collection
    • long segment of inflammation on imaging
• intravenous fluids
• analgesics
• CT-guided drainage of larger abscesses
• surgery (colectomy)
  • >= 3 acute attacks of diverticulitis
  • a single attack
    • requiring hospitalization in a patient < 40 years of age
    • evidence of perforation, colonic obstruction, peritonitis, sepsis or inflammatory involvement of the urinary tract
    • recurrent & persistent symptoms after a diverticulitis episode
  • inability to rule out colon carcinoma
  • for perforated bowel, surgical resection comparable to peritoneal lavage in complications (26-31%) & overall mortality (12-14%), but less likely to need reoperation & sigmoid colon cancers may be revealed during surgery
  • > 50% of elective colectomy surgeries for diverticulitis do not meet guideline criteria
  • absolute risks of readmission & emergency surgery are low after nonoperative management of diverticulitis
    • 5 year risk of readmission = 9%
    • 5 year risk of emergency surgery = 2%
  • elective colectomy does not prevent subsequent emergency surgery
  • decision for surgery should be individualized
    • not based solely on number of diverticulitis episodes
• diet
  • nothing by mouth (NPO) in hospitalized patients
    • resume diet slowly after symptoms have improved
  • liquid diet for outpatients
  • low-residue diet with stool softener after resolution of acute attack (prevention of recurrence)
  • gradual increase in dietary fiber to 25-35 gm/day
  • fiber from fruits & cereals, but not vegetables, associated with decreased risk for diverticulitis in women
  • high-quality diet (high-fiber, vegetarian)
• other preventive measures
  • regular physical activity
  • normal body-mass index
  • smoking cessation
  • avoid NSAIDs (except low-dose aspirin)
  • no medications are proven to lower risk for recurrence

Follow-up:

• colonoscopy 1-2 months after recovery or persistent symptoms
  • evaluate extent of disease
  • evidence of malignancy (colon cancer)
    • incidence of colorectal cancer in patients with uncomplicated diverticulitis is very low (1.1%)
    • colonoscopy may be unnecessary after radiologically proven uncomplicated diverticulitis
  • evidence of stricture
• barium enema
• abdominal CT for persistent symptoms
• recurrent attacks are common
  • recurrence after 1st episode: 8% at year, 17% at 5 years, 22% at 10 years
  • recurrence after 2nd episode: 19% at year, 44% at 5 years, 55% at 10 years

More general terms

• diverticulosis
• gastrointestinal infection
• bacterial infection

Patient information

diverticulitis patient information