Diverticulitis

Epidemiology

  • Mean Age for Admission for Acute Diverticulitis: 63 y/o
    • However, 16% of admissions for acute diverticulitis occur in patients <45 y/o
  • Association with Diverticulosis (see Diverticulosis, [[Diverticulosis]]): 15-25% of patients with diverticulosis will develop diverticulitis

Microbiology

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Physiology

  • Microscopic/Macroscopic Perforation of Diverticulum: results in inflammation and focal necrosis

Diagnosis

  • Complete Blood Count (CBC)
    • Leukocytosis: however, leukocytosis is absent in 45% of cases
  • KUB: non-specific findings may be seen in 30-50% of cases
    • Air-Fluid Levels with Small Bowel/Colonic Dilatation: due to ileus or obstruction
    • Soft Tissue Density: due to abscess
    • Pneumoperitoneum (on upright KUB): may be seen (due to perforation) in 3-12% of cases
  • Abdominal Ultrasound
    • Hypoechoic Peridiverticular Inflammation
    • Mural and Peridiverticular Abscess with//without Gas Bubbles
    • Bowel Wall Thickening at the Point of Maximal Tenderness: defined as mural wall thickness >4 mm
    • Presence of Diverticula in Surrounding Segments
  • Abdominal/Pelvic CT Scan: 94% sensitivity/99% specificity
    • Localized Colonic Wall Thickening: wall thickness >4 mm
    • Increased Soft Tissue Density within the Pericolonic Fat (Due to Inflammation or Fat Stranding)
    • Presence of Colonic Diveticula
  • Abdominal/Pelvic MRI: may be useful, although CT is usually preferred
  • Water-Soluble Contrast Enema: may demonstrate extravasated contrast, although CT is usually preferred
    • Barium and air (double) contrast technique is contraindicated: due to the risk of perforation/peritonitis

Clinical Manifestations

General Comments

  • Features of Complicated Diverticulitis: acute/chronic complications occur in 25% of acute diverticulitis cases
    • Small Intestinal/Colonic Obstruction
    • Colonic Perforation
    • Diverticular Abscess
    • Fistula

Gastrointestinal Manifestations

Abdominal Pain (see Abdominal Pain, [[Abdominal Pain]])

  • Epidemiology: most common complaint
  • Location: usually located in the left lower quadrant (LLQ), due to involvement of the sigmoid colon
    • Abdominal pain may occur in the suprapubic region: in cases cases with redundant sigmoid colon
    • Abdominal pain may occur in the right lower quadrant (RLQ): in cases with redundant sigmoid colon or in cases with right-sided cecal diverticulitis (which is more common in Asian populations)
  • Character
    • Abdominal pain is usually constant
    • Abdominal pain is often present for several days prior to presentation
    • 50% of patients have had one or more prior episodes of similar abdominal pain
  • Chronic Abdominal Pain: approximately 20% of patients with prior acute diverticulitis will develop chronic abdominal pain
    • May be due to underlying irritable bowel syndrome
    • May be due to low-grade/smoldering diverticulitis (with persistent diverticular inflammation)

Change in Bowel Habits/Stools

  • Constipation (see Constipation, [[Constipation]]): present on 50% of cases
  • Diarrhea (see Diarrhea, [[Diarrhea]]): present in 25-35% of cases
  • Positive Stool Occult Blood: may be present (although hematochezia is rare)

Nausea/Vomiting (see Nausea and Vomiting, [[Nausea and Vomiting]])

  • Epidemiology: occurs in 20-62% of cases
  • Mechanisms
    • Bowel Obstruction
    • Ileus
    • Peritoneal Irritation

Tender, Abdominal Mass (see Abdominal Mass, [[Abdominal Mass]])

  • Epidemiology: present in 20% of cases
  • Mechanism
    • Peri-Colonic Inflammation
    • Peri-Diverticular Abscess

Localized Peritoneal Signs

  • Localized Guarding
  • Localized Rebound Tenderness
  • Localized Rigidity

Rectal Mass/Tenderness

  • Due to distal sigmoid abscess

Other Manifestations

  • Fever (see Fever, [[Fever]]): usually low-grade
  • Urinary Frequency/Urgency/Dysuria (see Dysuria, [[Dysuria]]): occurs in 10-15% of cases (due to bladder irritation from adjacent inflammed sigmoid colon)

Complications

Colonic Obstruction (see Colonic Obstruction, [[Colonic Obstruction]])

  • Mechanism
    • Extrinsic colonic compression by peri-colonic inflammation or abscess during acute diverticulitis episode
  • Clinical
    • Usually partial obstruction: high-grade colonic obstruction is rare (except in cases with colonic structures from chronic diverticular inflammation)

Small Bowel Obstruction (SBO) (see Small Bowel Obstruction, [[Small Bowel Obstruction]])

  • Mechanisms
    • Loop of small intestine becomes entrapped in a peri-colonic inflammatory mass
    • Localized irritation with associated ileus

Colonic Perforation (see Colonic Perforation, [[Colonic Perforation]]): due to rupture of diverticular abscess into peritoneal space

  • Epidemiology: only 1-2% of acute diverticulitis cases result in colonic perforation with purulent/fecal peritonitis
    • However, these cases are associated with an approximate 20% mortality rate

Diverticular Abscess

  • Epidemiology
    • Abscess occurs in 17% of patients hospitalized with acute diverticulitis
    • Abscess occurs in 16% of patients with acute diverticulitis without peritonitis
  • Clinical
    • May be noted on initial CT scan or may develop precipitously
    • Abscess should be suspected in patients with uncomplicated diverticulitis without clinical response (in abdominal pain and fever) to 3 days of antibiotics

Fistula

  • Epidemiology: occurs in 20% of patients with surgically-treated diverticulitis
  • Mechanism: colonic inflammation -> fistulization between the colon and adjacent viscera (most commonly the bladder)
  • Clinical
    • Colovesical Fistula: may result in pneumaturia, fecaluria, dysuria
    • Colovaginal Fistula: may result in vaginal passage of feces or flatus

Pyogenic Liver Abscess (see Pyogenic Liver Abscess, [[Pyogenic Liver Abscess]])

  • Epidemiology: occurs rarely (due to spread of infection via the portal circulation)

Sepsis (see Sepsis, [[Sepsis]])

  • Epidemiology: rare (usually associated with perforation and/or peritonitis)

Recurrent Diverticulitis

  • Recurrence Rates
    • Recurrence Rate After First Episode of Acute Diverticulitis: 33%
    • Recurrence Rate After Second Episode of Acute Diverticulitis: 33%
  • Complication Rates with Recurrent Diverticulitis: recurrent episodes of diverticulitis are not associated with higher incidence of complications than the first episode

Treatment

Antibiotics

General Principles

  • Coverage: provide coverage for Gram-negative organisms and anerobes
  • Recovery of More Than One Organism: indicates presence of polymicrobial infection
    • In which case, anaerobic coverage should be continued (even if no anaerobes are isolated)

First-Choice Antibiotic Regimens

Alternative Antibiotic Regimens

Surgical Management

Surgical Goals

  • Removal of Septic Focus
  • Treatment of Bowel Obstruction or Fistula
  • Restoration of Bowel Continuity

Need for Surgical Intervention

  • All Patients with Acute Diverticulitis: 20% of patients with require surgical intervention at some point during the course of the disease
    • Almost all patients who undergo surgical intervention have either had complicated diverticulitis or experienced several recurrent episodes of diverticulitis
  • Systematic Review of Sigmoid Diverticulitis (2014) [MEDLINE]: in recurrent diverticulitis, the incidence of chronic pain is 5-25% in patients managed operatively vs 20-35% in patients managed non-operatively

Absolute Indications for Surgical Management

  • Abscess with Failure to Respond to Percutaneous Drainage
  • Clinical Deterioration or Failure to Improve with Medical Therapy
  • Enterocutaneous Fistula
  • Inability to Exclude Colon Cancer
  • Intractable Symptoms
  • Bowel Obstruction
  • Peritonitis
  • Recurrent Diverticulitis

Relative Indications for Surgical Management

  • Age <40 y/o
  • Immunosuppression
  • Right-Sided Diverticulitis
  • Symptomatic Stricture

Technique

  • Laparoscopic Resection: probably best suited for patients with resolved acute diverticulitis and in patients with Hinchey stage I/II disease
  • Open Resection: may be required

Hinchey’s Classification of Peritoneal Contamination

  • Stage I: pericolic or mesenteric peritonitis
  • Stage II: walled-off pelvic abscess
  • Stage III: generalized purulent peritonitis
  • Stage IV: generalized fecal peritonitis

Surgical Mortality Rate

  • Mortality Rate: 1.3-5% (depends on severity of illness and presence of co-morbid conditions)

References

  • Sigmoid diverticulitis: a systematic review. JAMA. 2014 Jan 15;311(3):287-97. doi: 10.1001/jama.2013.282025 [MEDLINE]