Diverticulitis 

Acute Diverticulitis: Inflammation of a diverticulum, a sac-like protrusion from the colon wall, due to micro-perforation.Diverticular Disease: Encompasses the spectrum of presentations and complications of diverticulosis.

• Diverticulosis: Presence of small outpouchings of the intestinal wall (diverticula)
  • occurring in 10% of people over 45 years and 65% of those over 70 years.
• Prevalence: Affects men and women equally, increases with age, most common in the sigmoid colon, and more prevalent in the right colon in Asian populations.
• Development: Thought to develop due to pressure-induced diverticula formation, related to low fiber intake.
• Symptomatic Cases: Only 15-20% are symptomatic; of these, only 25% develop diverticulitis.

Etiology

• Diet: Low fiber, high fat, and red meat increase risk.
• Lifestyle: Obesity and smoking.
• Medications: NSAIDs, steroids, opiates (increase risk), statins (decrease risk).
• Misconceptions: Nuts, seeds, and popcorn are not associated with increased risk.

Pathophysiology:

• Result of microscopic and macroscopic perforations of the diverticular wall.
• Previously attributed to obstruction of colonic diverticulum with fecaliths.
• Now theorized that food particles cause increased luminal pressure, leading to erosion and focal inflammation.
• Erosion leads to necrosis and subsequent perforation.
• Mesenteric fat may contain micro-perforations.
• Potential complications include local abscess formation, fistulization to adjacent organs, or intestinal obstruction.
• Frank bowel wall perforations can lead to peritonitis and death without rapid diagnosis and treatment.

Epidemiology

• Prevalence: Present in ~60% of people >60 years old.
• Diverticulitis Occurrence: 10% to 25% with diverticulosis.
• Hospitalizations: Increased by 26% from 1998 to 2005.
• Demographics:
  • More common in men <50 years and women 50-70 years.
  • Equal prevalence in men and women overall.
  • Age of admission: Mean 63 years.

Presentation:

Can be

• simple (uncomplicated) or
• complicated (abscess, fistula, obstruction, perforation).

DIVIDED TO

• Simple/Uncomplicated
  • Non-severe
    • Mild to moderate symptoms that do not indicate severe systemic infection or significant complications.
  • Severe disease if
    • systemic infection
    • peritonitis
    • inability to tolerate oral intake
    • failure of outpatient management
    • persistent fever
    • leukocytosis
    • worsening pain after two to three day
• Complicated
  • positive blood culture result,
  • sepsis or septic shock
  • abscess larger than 5 cm in diameter
  • fistula
  • perforation
  • obstruction
  • massive diverticular bleeding

History and Physical

Symptoms:

• Vary depending on disease severity
• Pain can be constant or intermittent
• Uncomplicated diverticulitis:
  • Left lower quadrant pain (Western nations) – Diverticulosis predominantly affects the sigmoid colon in Western populations, leading to left lower quadrant pain when inflamed.
  • Right-sided pain (Asian descent) – Epidemiological studies indicate a higher incidence of right-sided diverticulosis in Asian populations, resulting in right-sided abdominal pain during inflammation.
• Associated bowel habit changes:
  • diarrhea (35%)
  • constipation (50%)
• Nausea and vomiting possible, secondary to bowel obstruction.
• Fever common with abscesses and perforation.
• Dysuria, frequency, and urgency in cases of sympathetic cystitis (inflamed bowel in contact with bladder wall).

Physical Examination:

• Tenderness to palpation over the inflamed area due to peritoneal irritation.
• Mass palpable in about 20% of patients with abscess.
• Bowel sounds usually hypoactive, sometimes normoactive.
• Peritoneal signs (rigidity, guarding, rebound tenderness) indicate bowel wall perforation.
• Fever almost always present; hypotension and shock are uncommon.

Differential Diagnosis

• Cholangitis, cholecystitis, chronic mesenteric ischemia, constipation, enterovesical fistula, gynecological pain, inflammatory bowel disease, intestinal perforation, irritable bowel syndrome, large-bowel obstruction.

Investigations

Clinical Diagnosis:

• Can be made based on history and physical examination.
• Clinical diagnosis accuracy ranges from 24% to 68%.
• Hence, laboratory and radiological tests are essential for accurate diagnosis.

Laboratory Tests:

• Leukocytosis.
• Elevated acute phase reactants:
  • Erythrocyte sedimentation rate (ESR).
  • C-reactive protein (CRP).

Radiological Tests:

• CT Scan:
  • Preferred test for acute diverticulitis.
  • Use water-soluble oral or rectal contrast (if significant nausea/vomiting) and intravenous contrast if no contraindications.
  • Sensitivity, specificity, and negative predictive value > 97%.
  • Typical findings:
    • Bowel wall thickening.
    • Pericolic fat stranding.
    • Pericolic fluid.
    • Small abscesses confined to the colonic wall.
    • Contrast extravasation indicating intramural sinus and fistula formation.
• Abdominal Ultrasound:
  • Sensitivity: 84% to 94%.
  • Specificity: 80% to 93%.
  • Highly operator-dependent.
  • Limited use despite lower cost and easy availability.
• MRI:
  • Another diagnostic option.
  • Higher cost and no direct comparison with CT in terms of sensitivity or specificity.
  • CT is usually preferred.

Radiographs:

• Typically show nonspecific abnormalities such as bowel gas.
• Air-fluid levels present if intestinal obstruction is present.

Endoscopy:

• Avoided in suspected acute diverticulitis due to increased risk of perforation.
• Recommended colonoscopy six to eight weeks after symptoms resolve to rule out:
  • Malignancy.
  • Inflammatory bowel disease.
  • Colitis (if no recent colonoscopy).

Treatment

Non-Severe

• Simple analgesia
• Fluids
• Light diet when symptoms start to improve
• may not require antibiotic therapy
• Immunocompetent patients with uncomplicated left-sided diverticulitis do not routinely require antibiotics. Several randomised controlled trials have demonstrated that antibiotic therapy is not beneficial to these patients. 
• Antibiotic therapy is appropriate for patients with any of the following features:
  • immune compromise
  • right-sided diverticulitis
  • failure to improve after 72 hours of conservative treatment (ie no antibiotic therapy).
• Antibiotic therapy:
  • amoxicillin+clavulanate 875+125 mg orally, 12-hourly for 5 days.
    • For patients with hypersensitivity to penicillins, use:
  • trimethoprim+sulfamethoxazole 160+800 mg orally, 12-hourly for 5 days
    • PLUS
  • metronidazole 400 mg orally, 12-hourly for 5 days.   

Severe/Systemically unwell

• Peritonism, fever> 39, tachycardia, tachypnoea, hypotension, impaired consciousness, cyanosis, unable to tolerate oral intake
• Hospitalized for IV Abx – Empirical antibiotic therapy = three-drug regimen:

1. Gentamicin intravenously PLUS
2. metronidazole 500 mg intravenously, 12-hourly PLUS 
3. amoxicillin 2 g intravenously, 6-hourly OR ampicillin 2 g intravenously, 6-hourly;

• Bowel rest
• May need drainage of abscess

Complications and Outcomes of Acute Diverticulitis

• Complications:
  • Approximately 15% of patients with acute diverticulitis develop complications.
  • Complications include:
    • Pelvic abscess
    • Intestinal perforation
    • Bowel fistula
    • Peritonitis
    • Bowel obstruction
    • Sepsis
    • Bleeding per rectum
• Recurrent Episodes:
  • 20% to 50% of patients experience recurrent episodes of diverticulitis.
  • Multiple episodes do not directly increase the risk for complications.
  • Increased risk of fibrosis from recurrent episodes can lead to stricture formation and subsequent obstruction.
• Chronic Pain:
  • About 20% of patients may experience chronic abdominal pain.
  • Causes include irritable bowel syndrome or chronic low-grade diverticulitis.
  • Elective colectomy may be considered for symptom control.
• Elective Surgery:
  • Elective operations for diverticulitis have increased by approximately 30% since 1998.
• Mortality Rates:
  • Uncomplicated diverticulitis: Negligible mortality with appropriate conservative therapy.
  • Complicated diverticulitis requiring surgery: Approximately 5% mortality.
  • Perforation with resulting peritonitis: Increases mortality risk to 20%.

Follow up

• Needs colonoscopy after 6-8 weeks – confirm diagnosis, exclude malignancy
  • complicated diverticulitis the prevalence of colorectal cancer is approximately 10%. 
  • These patients should undergo colonoscopy 6 to 8 weeks after an episode of acute diverticulitis
• Recurrent attacks occur in 25%
• Cease smoking
• Dietary advise
  • increase the intake of dietary fibre
    • Studies have indicated that the most likely cause of diverticulitis is impacted faecal matter (rather than food) in diverticula.
    • Therefore the main strategy to prevent diverticulitis is to maintain a soft stool
  • avoid foods that could predispose to a further episode of diverticulitis, mainly corn, nuts and seeds – Given the no evidence for this dietary AFP suggest that patients should not be instructed to avoid these foods to reduce risk.

Diverticular bleeding

• is a common cause of large-volume lower gastrointestinal bleeding. 
• Diverticular bleeding stops spontaneously in 75% of cases. 
• If it continues, the site of bleeding may be localised with
  • Colonoscopy
  • red blood cell scanning
  • CT angiography. 
• Management
  • Haemostasis
  • urgent colonoscopy 
  • selective angiography with embolisation of the bleeding vessel.