Diverticulitis

See Also

Epidemiology

Lifetime Prevalence of acute Diverticulitis: 25%
As with Diverticulosis, Diverticulitis risk increases with age
Prevalence has increased in the U.S.
1. In 1980, Prevalence 115 per 100,000 person years
2. In 2007, Prevalence 188 per 100,000 person years
3. Bharucha (2015) Am J Gastroenterol 110(11): 1589-96 [PubMed]

Pathophysiology

Complicates 1 to 4% (up to >10% in some studies) of Diverticulosis
1. See Diverticulosis for the pathophysiology of Diverticuli
Distribution
1. Most often affects sigmoid colon (85% of Diverticuli in western societies)
2. Right Diverticuli (ascending colon) seen in age <60 years and asian patients (uncommon)
Inflammation of colonic Diverticula
1. Increased bowel intraluminal pressure and altered bowel motility
2. Inflammation
  1. Bacterial overgrowth
  2. Tissue ischemia
  3. Diverticulum becomes impacted with fecal material (fecalith)
    1. Undigested food and stool becomes trapped within the Diverticulum
    2. Fecal material hardens and erodes through bowel wall
3. Colon Perforation
  1. Microperforation (Simple, Localized, Uncomplicated Diverticulitis)
    1. Peridiverticulitis with localized phlegmon confined to mesentary
    2. Infection walled off by pericolic fat
  2. Macroperforation (Complicated Diverticulitis)
    1. Pericolic abscess or
    2. Free perforation with generalized peritonitis
    3. Fistulas may form between adjacent structures

Risk Factors

Increasing age over 45 years
Constipation
Obesity
Women
Sedentary
Family History
Low fiber diet
Diet high in red meat
Diet high in refined Carbohydrates
Tobacco Abuse
Medications
1. Aspirin
2. NSAIDS

Symptoms

Mild Anorexia
Fever or Chills
Diarrhea or obstipation
Abdominal Pain: Acute constant pain
1. Initial: Hypogastric pain
2. Later: Left Lower Quadrant Abdominal Pain (>92% in U.S.)
  1. In contrast, right sided Diverticulitis is more common in asian countries and in younger patients

Signs

Fever
1. Fever is typically <102 F
Tenderness over left lower quadrant
1. Isolated tenderness in Left lower quadrant is highly suggestive of Diverticulitis
Guarding, abdominal rigidity and Rebound Tenderness
1. Not sensitive or specific for Diverticulitis
2. May suggest peritonitis
Rectal mass or tenderness on Rectal Exam
1. May suggest pelvic abscess

Labs

Complete Blood Count
1. Leukocytosis (>55-68% of cases)
Comprehensive Metabolic Panel
1. Evaluate Electrolytes, Renal Function and differential diagnosis
Serum Lipase
1. Evaluate differential diagnosis
C-Reactive Protein
1. C-RP >50 mg/L consistent with Diverticulitis (LR+ 2.2, LR- 0.3)
2. C-RP >200 mg/L consistent with perforation (69% of cases)
Urinalysis
1. Dysuria and Urinary Frequency may be present in Diverticulitis (evaluate differential diagnosis)
Urine Pregnancy Test (or blood Qualitative hCG)
1. Evaluate differential diagnosis in women of reproductive age

Diagnosis

Combination Criteria (LR+ 18, LR- 0.65)
1. Left Lower Quadrant Abdominal Pain AND
2. Vomiting absent AND
3. C-RP >50 mg/L
Symptoms and signs
1. Localized left lower quadrant tenderness (LR+ 10.4, LR- 0.7)
2. Left Lower Quadrant Abdominal Pain: (LR+ 3.3, LR- 0.5)
3. Vomiting absent (LR+ 1.4, LR- 0.2)
4. Fever (LR+ 1.4, LR- 0.8)
Labs
1. C-Reactive Protein (C-RP) > 50 mg/L (LR+ 2.2, LR- 0.3)
Imaging
1. CT Abdomen (LR+ 94, LR- 0.1)
2. Ultrasound Abdomen (LR+ 9.2, LR- 0.09)
3. MRI Abdomen (LR+ 7.8, LR- 0.07)
References
1. Lameris (2010) Dis Colon Rectum 53(6): 896-904 [PubMed]
2. Wilkins (2013) Am Fam Physician 87(9): 612-20 [PubMed]

Differential Diagnosis

See Left Lower Quadrant Abdominal Pain
Appendicitis
Small Bowel Obstruction
Gastroenteritis
Inflammatory Bowel Disease
Inguinal Hernia (Incarcerated Hernia or Strangulated Hernia)
Urinary Tract Infection
Ureterolithiasis
Colitis (including Ischemic Colitis)
Pancreatitis
Women

Imaging
Abdominal CT (preferred)

Abdominal CT with IV contrast is the best overall imaging study to diagnose Diverticulitis
1. IV Contrast with oral water contrast is typical in most cases
2. IV Contrast with Oral Contrast is preferred if abscess is suspected
Abdominal CT is best test to confirm sigmoid Diverticulitis
1. Test Sensitivity: >94 (approaches 100% for sigmoid involvement)
2. Test Specificity: Approaches 100% (sigmoid involvement)
Abdominal CT is best test to identify complications (perforation)
Highest Test Sensitivity CT Findings suggestive of Diverticulitis
1. Pericolic fat infiltration or stranding
2. Bowel wall thickening
Highest Test Specificity CT Findings suggestive of Diverticulitis
1. Fascial thickening
2. Free Air
3. Inflamed Diverticulum
4. Intramural air or sinus tract
5. Abscess or Phlegmon
6. Muscle hypertrophy (Test Specificity 98% in Diverticulitis)
7. Arrowhead sign
  1. Localized bowel wall thickening
  2. Bowel lumen resembles arrow shape at Diverticulum
Disadvantages
1. See CT-associated Radiation Exposure
2. See Contrast-Induced Nephropathy
  1. CT may be delayed until after fluid Resuscitation and improved Renal Function
  2. In the interim, patient may be treated empirically with Antibiotics for Diverticulitis
References
1. Kaiser (2005) Am J Gastroenterol 100(4): 910-7 [PubMed]
2. Lameris (2008) Eur Radiol 18(11): 2498-511 [PubMed]

Imaging
Other

Abdominal flat and upright Abdomen
1. Observe for abdominal free air
2. Small Bowel Obstruction
Abdominal MRI
1. Consider in pregnancy
2. Not routinely used in practice for this indication
  1. High cost
  2. Long scan times (unacceptable in critically ill patients)
3. MRI findings are similar to CT, but with better resolution of soft tissue
  1. Buckley (2007) Eur Radiol 17(1): 221-7 [PubMed]
Abdominal Ultrasound
1. Not routinely used in practice for this indication (Disadvantages when compared with CT)
  1. Accuracy is highly dependent on operator experience
  2. Does not evaluate alternative diagnoses for Abdominal Pain (outside the Pelvis)
  3. Does not well define abscess extent
  4. Does not identify free air
  5. Limited by overlying gas, Obesity and pain
2. Reliable for diagnosis of sigmoid Diverticulitis but variable efficacy due to technique, body habitus and acute pain
  1. Schwerk (1992) Dis Colon Rectum 35(11): 1077-84 [PubMed]
3. Consider in women for evaluating additional Pelvic Pain causes (including pregnancy-related)
Avoid Colonoscopy in acute disease
1. Risk of worsening perforation
Avoid Barium Enema in acute disease
1. Risk of extravasation if perforation

Management
Approach

Indications for outpatient management
1. Uncomplicated Diverticulitis with mild pain or well controlled on Oral Analgesics
2. Stable clinically with normal Vital Signs without signs of peritonitis
3. Tolerating oral fluids
4. Exercise caution in discharging patients at higher risk of failed outpatient management
  1. Abdominal free fluid on imaging (esp. in women)
Uncomplicated Diverticulitis may be managed empirically without imaging or other studies
1. Focal Left Lower Quadrant Abdominal Pain AND
2. No peritoneal findings AND
3. Non-toxic appearance AND
4. No suspected alternative significant condition
Complicated Diverticulitis Criteria
1. Symptoms for 5 days or more
2. Peritonitis or obstruction
3. Rectal Bleeding
4. History of multiple episodes of Diverticulitis
5. Immunocompromised State
Advanced Imaging Indications (i.e. CT Abdomen for most patients)
1. Diagnosis unclear
  1. Not classic Left Lower Quadrant Abdominal Pain with fever
  2. Other diagnoses are of similar likelihood
2. Moderate to severe symptoms
3. Inability to tolerate oral fluids
4. Peritoneal signs
5. Failure to improve in 2-3 days

Management
Outpatient (Uncomplicated Diverticulitis)

See indications for uncomplicated Diverticulitis (88% of cases) as above
General Measures
1. Clear Liquid Diet and advance to soft mechanical diet as tolerated
2. Low fiber diet in acute phase
3. Avoid Opioids as much as possible (most Opioids increase intracolonic pressure)
4. Anticipate improvement within 48-72 hours
Antibiotic regimen (Outpatient Mangement of mild disease)
1. Consider no Antibiotics for acute uncomplicated Diverticulitis with reliable follow-up in 2-3 days
  1. Indications
    1. No abscess and no fistula AND
    2. No signs of severe infection or Sepsis AND
    3. No Immunosuppression AND
    4. Not pregnant AND
    5. No significant comorbidity
    6. (2015) Gastroenterology 149: 1944-9 [PubMed]
    7. Chabok (2012) Br J Surg 99(4): 532-9 [PubMed]
    8. Mora-Lopez (2021) Ann Surg 274(5): e435-42 [PubMed]
  2. Approach at 2-3 day follow-up
    1. Initiate Antibiotics if not improved at 2-3 days
2. Primary protocol (requires 2 agents for 7-10 days, covers Gram Negative aerobic and Anaerobic Bacteria)
  1. Antibiotic 1: Metronidazole (Flagyl) 500 mg orally every 6 to 8 hours AND
  2. Antibiotic 2 (choose one)
    1. Ciprofloxacin 500 mg orally twice daily OR
    2. Levofloxacin 750 mg orally every 24 hours OR
    3. Trimethoprim-Sulfamethoxazole 160/800 mg (Septra, Bactrim DS) orally twice daily
3. Alternative protocol (choose one Antibiotic for 7-10 days, covers Gram Negative aerobic and Anaerobic Bacteria)
  1. Augmentin 1000 mg orally twice daily OR
  2. Moxifloxacin 400 mg orally daily

Management
Inpatient (Complicated Diverticulitis)

Indications for hospitalization
1. Age >85 years
2. Significant inflammation, clinically unstable or with peritoneal signs
3. Unable to take oral fluids
4. Complicated Diverticulitis with moderate to severe pain
5. Abscess
6. Consider in patients at higher risk of failed outpatient management (abdominal free fluid on imaging, women)
General measures
1. Clear Liquid Diet may be initiated if tolerating oral fluids (otherwise NPO)
Precautions
1. E. coli resistance to Fluoroquinolones (e.g. Ciprofloxacin) is as high as 75% at some hospitals
Antibiotic regimen for moderate disease
1. Primary agents (choose one)
  1. Piperacillin-tazobactam (Zosyn) 3.375 g IV every 6 hours (or 4.5 g IV every 8 hours) OR
  2. Ticarcillin-clavulanate (Timentin) 3.1 g IV every 6 hours OR
  3. Ertapenem (Invanz) 1 g IV every 24 hours OR
  4. Moxifloxacin (Merrem) 400 mg IV every 24 hours
2. Alternative agents (choose one)
  1. Moxifloxacin 400 mg IV every 24 hours OR
  2. Tigecycline (Tygacil) 100 mg IV for dose 1, then 50 mg IV every 12 hours
3. Alternative agents: Combination (choose two agents)
  1. Antibiotic 1: Metronidazole (Flagyl) 500 mg IV every 6 to 8 hours (or 1 g IV every 12 hours) AND
  2. Antibiotic 2 (choose one)
    1. Ciprofloxacin 400 mg IV every 12 hours OR
    2. Levofloxacin 750 mg IV every 24 hours OR
    3. Cefazolin 1 to 2 g IV every 8 hours OR
    4. Cefuroxime 1.5 g IV every 8 hours OR
    5. Cefotaxime 1 to 2 g IV every 8 hours
Antibiotic regimen for severe disease (e.g. ICU, life-threatening)
1. Primary agents (choose one)
  1. Consider primary agents listed above under moderate disease (e.g. Zosyn, Invanz, Merrem)
  2. Imipenem-Cilastin (Primaxin) 500 mg IV every 6 hours OR
  3. Meropenem (Merrem) 1 g IV every 8 hours OR
  4. Doripenem (Doribax) 500 mg IV every 8 hours (not available in U.S.)
2. Alternative agents: Three agent protocol (choose 3)
  1. Ampicillin 2 g IV every 6 hourss AND
  2. Metronidazole 500 mg IV every 6 to 8 hours AND
  3. Aminoglycoside (choose one, pharmacy to monitor levels)
    1. Gentamicin OR
    2. Tobramycin OR
    3. Amikacin
3. Alternative agents: Two agent protocol
  1. Antibiotic 1: Metronidazole 500 mg IV every 6 to 8 hours AND
  2. Antibiotic 2 (choose one)
    1. Cefepime 2 g IV every 8 hours OR
    2. Ceftazidime (Fortaz) 2 g IV every 8 hours
4. Alternative agents: Three agent protocol (choose 3)
  1. Ampicillin 2 g IV q6 hours AND
  2. Metronidazole 500 mg IV every 6 to 8 hours AND
  3. Fluoroquinolone (choose one)
    1. Ciprofloxacin 400 mg IV every 12 hours or
    2. Levofloxacin 750 mg IV every 24 hours
Disposition: Discharge Indications
1. Vital Signs have normalized
2. Tolerating oral intake
3. Pain resolved or improved and controlled on Oral Analgesics

Management
Complicated Diverticulitis Requiring Surgical Intervention

Surgical intervention is required in 15-30% of hospitalized patients with acute Diverticulitis
CT-guided percutaneous drainage Indications
1. Localized Abscess >3 cm (or smaller abscesses that are not improving on IV Antibiotics)
Laparoscopic or open surgery Indications
1. Hinchey Stage 3 or 4 (generalized purulent or feculent peritonitis)
2. Laparoscopy is preferred over open procedure (fewer complications, less mortality and faster recovery)
3. Abscess drainage or Washout procedure
4. Emergency Colectomy
  1. High morbidity (Pneumonia, Acute Coronary Syndrome or Respiratory Failure)
  2. Increased mortality (especially in elderly)
  3. Colectomy with primary anastomosis performed at initial procedure
    1. Safe despite Diverticulitis in selected patients
  4. Colectomy with multi-stage, delayed re-anastomosis (Hartmann Procedure)

Course

Improves on Antibiotics within 48 to 72 hours

Follow-up

Colonoscopy
1. Do not perform in acute Diverticulitis
  1. Risk of bowel perforation
2. Obtain 6 to 8 weeks after complicated Diverticulitis episode
  1. Colorectal Cancer risk 7.9% in complicated Diverticulitis (1.3% in uncomplicated)
  2. May not be needed in uncomplicated first-episode empirically treated Diverticulitis
  3. May also not be needed if last high quality Colonoscopy within last year
  4. Consider also if approaching routine screening or if findings suggest other indication
  5. lau (2011) Dis Colon Rectum 54(10): 1265-70 [PubMed]
  6. Westwood (2011) Br J Surg 98(11): 1630-4 [PubMed]
3. Findings
  1. Define extent of Diverticulosis
  2. Evaluate for Colon Cancer
  3. Barium Enema may be used as alternative option
Surgical indications for prevention of recurrent Diverticulitis
1. Recurrent uncomplicated Diverticulitis requiring hospitalization following third episode
2. Abscess formation requiring drainage
3. Other contributing risk factors for recurrence
  1. Age over 50 years
  2. Tobacco Abuse
  3. Obstruction
  4. Peritonitis
  5. Fistula

Complications

Generalized peritonitis
Microperforation
1. Small air bubbles are seen in or adjacent to the bowel wall, but Oral Contrast is contained within the bowel
Colonic perforation
1. Increased risk in Immunocompromised patients and in Chronic Opioid, Corticosteroid or NSAID use
Colonic abscess (~10% of cases)
1. Small abscess (<3 cm) is conservatively treated wih IV Antibiotics (percutaneous drainage if not improving)
2. Large abscess (>3 cm) is initially treated with percutaneous drainage and IV Antibiotics
  1. Surgery indicated for persistent fever >48 hours or abscess not amenable to percutaneous drainage
Colonic fistula
1. May present with fecaluria, Pneumaturia, pyuria or stool per vagina
2. Consult colorectal surgery
Obstruction
1. Obstructive Diverticulitis requires surgical resection
Persistent pain following Diverticulitis
1. Obtain Fecal Calprotectin
  1. May differentiate chronic inflammation from visceral Hypersensitivity (e.g. Irritable Bowel Syndrome)
  2. Fecal Calprotectin <15 mcg/g suggests Irritable Bowel Syndrome
  3. Consider chronic Diverticular inflammation if Fecal Calprotectin >15 mcg/g
  4. Tursi (2009) Int J Colorectal Dis 24(1): 49-55 [PubMed]
2. Consider C-Reactive Protein (if calprotectin not available)
3. Consider repeat CT Abdomen and Pelvis
4. Consider Colonoscopy (if at least 6 to 8 weeks after acute Diverticulitis)

Prevention

Dietary changes
1. High fiber diet (except in acute phase - see above)
2. Vegetarian Diet
3. High quality diet with reduced meat intake (e.g. Mediterranean Diet)
Maintain adequate hydration
Exercise or Physical Activity
Avoid NSAIDs
Weight loss (if BMI >30 kg/m2)
1. Ideal Body Mass Index target 18 to 25 kg/m2
Tobacco Cessation
1. Tobacco use is associated with complicated Diverticulitis and worse outcomes
2. Turunen (2010) Scand J Surg 99(1): 14-17 [PubMed]
No evidence that avoiding nuts, corn or popcorn decreases Diverticulitis risk
1. Strate (2008) JAMA 300(8): 907-14 [PubMed]
Avoid Mesalamine in the prevention of Diverticulitis recurrence (not effective)
1. Carter (2017) Cochrane Database Syst Rev (10): CD009839 [PubMed]

Prognosis

Peritonitis Mortality
1. See Mannheim Peritonitis Index (Clinical Scoring System to Predict Mortality in Peritonitis)
2. Hospitalized patients with acute Diverticulitis have up to a 1% mortality rate (5.5% if perforation)
  1. Makela (2010) Dig Surg 27(3): 190-6 [PubMed]
Diverticulitis recurrence risk
1. After first episode, recurs in 9-30% (mean 22%) of cases within 10 years
2. After second episode, recurs in 50 to 55% of cases within 10 years

References

Baker and Maldonado (2021) Crit Dec Emerg Med 35(7): 27
Gilbert (2015) Sanford Guide to Antimicrobials
Kleinmann (2023) Crit Dis Emerg Med 37(2): 22-9
Simmang in Feldman (1998) Gastrointestinal, p. 1793-7
Swadron and Inaba in Herbert (2018) EM:Rap 18(9): 14-5
Bailey (2022) Am Fam Physician 106(2): 150-6 [PubMed]
Hammond (2010) Am Fam Physician 82(7): 766-70 [PubMed]
Salzman (2005) Am Fam Physician 72:1229-42 [PubMed]
Stollman (2004) Lancet 363(9409): 631-9 [PubMed]
Wilkins (2013) Am Fam Physician 87(9): 612-20 [PubMed]