Acute Diverticulitis

1. Topic Overview

Summary

Acute diverticulitis is inflammation and/or infection of colonic diverticula, representing one of the most common complications of diverticular disease. It predominantly affects the sigmoid colon in Western populations, with a characteristic presentation of left lower quadrant pain, fever, and altered bowel habit. The condition affects up to 25% of individuals with diverticulosis during their lifetime, with increasing incidence in younger adults under 50 years. [1]

Diagnosis is primarily confirmed by CT abdomen/pelvis with intravenous contrast, which demonstrates pericolic fat stranding, bowel wall thickening, and complications such as abscess or perforation. The modified Hinchey classification system stratifies disease severity from uncomplicated (Hinchey 0-Ia) to complicated cases with purulent or faecal peritonitis (Hinchey III-IV). [2]

Management paradigms have shifted significantly over the past decade. Recent randomized controlled trials (AVOD, DIABOLO, DIVA) have demonstrated that uncomplicated diverticulitis can be managed successfully without antibiotics in selected patients, challenging traditional antibiotic-centric approaches. [3,4] Complicated disease requires more intensive management including CT-guided drainage for large abscesses, and emergency surgery for perforated disease with peritonitis.

Key Facts

• Definition: Inflammation/infection of colonic diverticula with transmural extension
• Location: Sigmoid colon (90-95% in Western populations); right-sided predominance in Asia (70% of cases)
• Prevalence: 4-5% of patients with diverticulosis develop acute diverticulitis; 25% lifetime risk once diverticulosis is established
• Incidence: 188 per 100,000 population per year; 50% increase over the past 20 years [1]
• Classic Presentation: Left lower quadrant pain (93%), fever (57%), leucocytosis (69%)
• Investigation: CT abdomen/pelvis with IV contrast (sensitivity 94%, specificity 99%) [5]
• Classification: Modified Hinchey staging (0 to IV)
• Recurrence: 13-23% after first episode; 40-50% after second episode [6]

Clinical Pearls

"Left-Sided Appendicitis": This classic teaching describes diverticulitis as "left-sided appendicitis" with LLQ pain, fever, and raised inflammatory markers. However, right-sided diverticulitis occurs in 5-10% of Western cases and up to 70% of Asian patients, creating diagnostic confusion with acute appendicitis. Right-sided disease tends to occur in younger patients (mean age 43 vs 63 years for left-sided) and has lower complication rates. [7]

Antibiotics Not Always Needed: Landmark trials AVOD (2012) and DIABOLO (2017) demonstrated that uncomplicated diverticulitis (Hinchey 0-Ia) can be safely managed with observation alone in immunocompetent patients. Meta-analysis shows no difference in complications, perforation rates, or need for surgery between antibiotic and non-antibiotic strategies (RR 0.93, 95% CI 0.71-1.22). [3,4] This represents a paradigm shift from routine antibiotics to selective use.

Colonoscopy After Recovery: Follow-up colonoscopy is recommended 6-8 weeks after an episode of diverticulitis to exclude underlying colorectal malignancy, which can mimic diverticulitis in 1.6-11% of cases. [8] Colonoscopy should NOT be performed during acute episodes due to perforation risk (estimated 0.3% but up to 5% in acute inflammation).

Young Patients Are Not More Severe: Historical teaching suggested aggressive disease in younger patients, but recent evidence refutes this. Outcomes are similar across age groups when stratified by Hinchey stage; younger patients do NOT require more aggressive surgical intervention. [9]

Why This Matters Clinically

Diverticulitis represents a major public health burden with over 300,000 hospitalizations annually in the United States alone, costing approximately $2.6 billion in healthcare expenditure. [1] Emergency physicians, general surgeons, and gastroenterologists must recognize uncomplicated from complicated disease to guide appropriate management pathways.

The paradigm shift toward observation-based management for uncomplicated disease reduces antibiotic exposure, antimicrobial resistance, and healthcare costs without compromising patient safety. Conversely, delayed recognition of complicated disease (abscess, perforation) leads to increased morbidity (50% in delayed surgery) and mortality (15-25% for faecal peritonitis). [10]

Understanding the evidence base allows clinicians to de-escalate care safely in low-risk patients while intensifying management appropriately in high-risk scenarios, optimizing both individual and population-level outcomes.

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2. Epidemiology

Incidence & Prevalence

Diverticulosis Prevalence:

• Age-dependent increase: 30% by age 50; 50% by age 60; 70% by age 80 [11]
• Asymptomatic in 70-80% of cases
• Predominantly left-sided (sigmoid) in Western populations (90-95%)

Diverticulitis Incidence:

• Annual incidence: 188 per 100,000 population (USA data)
• 50% increase in incidence over the past two decades, particularly in adults less than 40 years [1]
• Lifetime risk of diverticulitis in patients with diverticulosis: 4-5% (older studies suggested 25%, but modern cohort data suggest lower rates)
• First episode: 80% uncomplicated; 20% complicated [12]

Hospital Admissions:

• 283,000 admissions per year in USA (2015 data)
• Emergency admissions account for 75% of cases
• Admission rates increasing despite improved outpatient management due to aging population

Temporal Trends:

• Rising incidence in younger adults (less than 50 years): 132% increase from 1998 to 2005 [13]
• Possible explanations: improved imaging detection, changing dietary patterns, obesity epidemic
• Earlier age of first presentation: median age 38 years for younger cohort vs 63 years for older cohort

Demographics

Risk Factors

Protective Factors:

• High dietary fiber (> 30g/day): RR 0.6 (weak evidence) [16]
• Regular physical activity (> 5 hours/week): RR 0.7
• Vegetarian diet: RR 0.7
• Aspirin use: Conflicting data; may reduce inflammation but increase bleeding risk

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3. Pathophysiology

Molecular and Cellular Mechanisms

Step 1: Diverticulum Formation (Diverticulosis)

Anatomical Basis:

• Colonic diverticula are false diverticula (pulsion type): herniation of mucosa and submucosa through the muscularis propria
• Occur at sites of weakness where vasa recta penetrate the circular muscle layer (antimesocolic border predominantly)
• Sigmoid colon most affected due to smallest luminal diameter (Law of Laplace: P = 2T/r; higher intraluminal pressure required to propel contents through narrow lumen)

Pathogenic Mechanisms:

1. Collagen Abnormalities: Altered type III collagen ratios reduce tensile strength; increased elastin deposition causes muscle thickening and dysmotility [23]
2. Enteric Nervous System Dysfunction: Reduced neuronal cell bodies and interstitial cells of Cajal lead to uncoordinated peristalsis and segmentation
3. Chronic Low-Grade Inflammation: Elevated IL-6, TNF-α, and calprotectin even in asymptomatic diverticulosis [24]
4. Microbiome Alterations: Reduced diversity (↓ Bacteroidetes, ↑ Proteobacteria) and loss of butyrate-producing species (Faecalibacterium prausnitzii)

Step 2: Inflammation and Infection (Diverticulitis)

Initiating Event — "Microperforation Theory":

• Obstruction of diverticulum neck by inspissated stool (fecalith) → ↑ intraluminal pressure
• Compromised venous drainage → mucosal ischaemia → erosion and microperforation
• Bacterial translocation across damaged mucosa

Inflammatory Cascade:

1. Innate Immune Activation: Pattern recognition receptors (TLR4, NOD2) recognize bacterial PAMPs → NF-κB activation → cytokine release (IL-1β, IL-6, IL-8, TNF-α)
2. Neutrophil Recruitment: Chemokines (CXCL8/IL-8) attract neutrophils → phagocytosis and oxidative burst → collateral tissue damage
3. Adaptive Immunity: Th1/Th17 polarization → IFN-γ and IL-17 production → chronic inflammation

Microbiology:

• Polymicrobial infection: Gram-negative aerobes (E. coli, Klebsiella) + anaerobes (Bacteroides fragilis, Prevotella)
• Biofilm formation on diverticular mucosa perpetuates inflammation
• Dysbiosis: 50% reduction in microbial diversity during acute episodes [25]

Step 3: Complications

Abscess Formation:

• Microperforation with localized peritoneal contamination → fibrinous adhesions wall off infected fluid
• Pericolic abscess (Hinchey Ib): less than 5cm, adjacent to inflamed segment
• Distant abscess (Hinchey II): Pelvic, intra-abdominal, or retroperitoneal spread via fascial planes

Perforation:

• Contained perforation: Omentum and adjacent structures seal defect → abscess
• Free perforation: Insufficient sealing → purulent (Hinchey III) or faecal (Hinchey IV) peritonitis
• Risk factors for perforation: NSAIDs, corticosteroids, immunosuppression, delayed presentation

Fistula Formation:

• Chronic inflammation → adhesion to adjacent viscera → transmural necrosis → fistulous tract
• Colovesical fistula (65% of diverticular fistulae): Pneumaturia, faecaluria, recurrent UTIs
• Colovaginal fistula (25%): Vaginal passage of stool/flatus; more common post-hysterectomy
• Coloenteric fistula (10%): Colon-to-small bowel; causes chronic diarrhea and malabsorption
• Colocutaneous fistula (rare): Spontaneous or post-surgical

Stricture Formation:

• Repeated episodes → fibrosis and muscular hypertrophy → luminal narrowing
• Presents as subacute obstruction; difficult to differentiate from malignancy

Segmental Colitis Associated with Diverticulosis (SCAD):

• Endoscopic inflammation between diverticula, sparing the diverticula themselves
• Pathogenesis unclear; possibly mucosal ischaemia or fecal stasis
• Clinically mimics IBD; treat with 5-ASA compounds

Modified Hinchey Classification

The Hinchey classification, originally developed for perforated diverticulitis in 1978 and modified by Kaiser et al. (2005), stratifies disease severity based on CT findings and operative findings: [2]

Prognostic Implications:

• Hinchey 0-Ia: less than 5% risk of progression to complicated disease with appropriate treatment
• Hinchey Ib-II: 20-30% require surgical intervention (drainage or resection)
• Hinchey III-IV: 100% require surgery; mortality rates 10-35% depending on comorbidities and timing of intervention [10]

Genetic and Molecular Insights

Recent genome-wide association studies (GWAS) have identified susceptibility loci:

• TNFSF15 (chr9q32): Encodes TL1A, a TNF superfamily cytokine involved in intestinal inflammation
• COLQ3A1 (chr2q32): Encodes type III collagen; variants associated with earlier onset and recurrent disease [21]
• FAM155A (chr13q33): Unknown function; associated with diverticular disease risk

Epigenetic modifications (DNA methylation patterns) differ between diverticulosis and diverticulitis, suggesting additional layers of regulation.

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4. Clinical Presentation

Symptoms

Typical Presentation (Uncomplicated Diverticulitis):

• Left lower quadrant pain (90-93%): Constant, dull, cramping; worsens over 24-72 hours; exacerbated by movement and eating
• Fever (40-60%): Low-grade (less than 38.5°C) in uncomplicated; high-grade suggests abscess or perforation
• Altered bowel habit (50-70%): Constipation (more common due to luminal narrowing) or diarrhea (secondary to adjacent inflammation)
• Nausea ± vomiting (20-30%): More common with proximal sigmoid involvement
• Bloating and distension (30-40%): Ileus or partial obstruction
• Urinary symptoms (12-15%): Frequency, dysuria, urgency (bladder irritation from adjacent inflammation; consider fistula if pneumaturia or faecaluria present)

Atypical Presentations:

• Right lower quadrant pain: Right-sided diverticulitis (more common in Asian populations); mimics appendicitis [7]
• Suprapubic pain: Pelvic abscess
• Flank pain: Retroperitoneal extension or ureteric involvement
• Painless rectal bleeding: Diverticular hemorrhage (different entity; usually NOT associated with acute diverticulitis)

Complicated Diverticulitis:

• Pneumaturia (air in urine; "champagne urine"): Pathognomonic for colovesical fistula
• Faecaluria (stool in urine): Colovesical fistula
• Vaginal passage of stool/flatus: Colovaginal fistula
• Generalized abdominal pain with rigidity: Perforation with diffuse peritonitis (Hinchey III-IV)
• Obstructive symptoms (vomiting, absolute constipation, pain): Stricture or abscess compressing bowel lumen

Signs

General Inspection:

• Unwell appearance, lying still (peritonitic pain worsened by movement)
• Fever: 37.5-38.5°C (uncomplicated); > 38.5°C (abscess/perforation)
• Tachycardia (> 100 bpm): Suggests sepsis or dehydration
• Hypotension: Late sign; indicates septic shock (Hinchey III-IV)

Abdominal Examination:

• Inspection: Distension (ileus, obstruction); previous surgical scars
• Palpation:
  • "Left lower quadrant tenderness (90%): Localized over sigmoid colon"
  • "Palpable mass (20%): Phlegmon, abscess, or inflamed bowel loop"
  • "Guarding/rigidity (5-10% uncomplicated; 80% complicated): Peritonitis (Hinchey III-IV)"
  • "Rebound tenderness: Peritoneal inflammation"
• Percussion: Tympany (ileus); dullness (abscess or mass); loss of liver dullness (pneumoperitoneum)
• Auscultation: Reduced bowel sounds (ileus); absent sounds (peritonitis); high-pitched tinkling (obstruction)
• Digital rectal examination: Tenderness (pelvic abscess); mass (rectal involvement rare); blood (rule out malignancy, ischaemic colitis)

Red Flags — Indicators of Complicated Disease

[!CAUTION] Immediate Surgical Referral Required:

• Generalized peritonitis (rigid, board-like abdomen; absent bowel sounds)
• Septic shock (hypotension, tachycardia, altered mental status, oliguria)
• Pneumaturia or faecaluria (fistula; requires semi-elective resection)
• Large abscess > 5cm on CT (likely requires drainage)
• Free intraperitoneal air (pneumoperitoneum on erect CXR or CT)
• Immunocompromised patient (30-50% complication rate; often minimal abdominal signs despite severe disease)
• Failure to improve after 48-72 hours of antibiotics (suggests abscess, ongoing perforation, or alternative diagnosis)
• Complete bowel obstruction (absolute constipation, feculent vomiting, grossly distended abdomen)

Differential Diagnosis

Diverticulitis must be differentiated from other causes of acute abdomen:

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5. Investigations

First-Line Laboratory Tests

Imaging

CT Abdomen/Pelvis with IV Contrast — Gold Standard [5]

Indications:

• All patients with suspected acute diverticulitis (confirm diagnosis, exclude complications)
• Sensitivity 94% (range 90-98%); Specificity 99% (range 96-100%)
• Accuracy 98% for detecting complications (abscess, perforation, fistula)

Typical Findings:

1. Uncomplicated Diverticulitis (Hinchey 0-Ia):

   • Colonic wall thickening > 4mm (mean 10-15mm)
   • Pericolic fat stranding (inflammatory exudate in mesentery)
   • Pericolonic soft tissue/phlegmon (Hinchey Ia)
   • Diverticula present (though absence doesn't exclude diagnosis in 10% of cases)

2. Complicated Diverticulitis:

   • Abscess (Hinchey Ib-II): Well-defined fluid collection with enhancing wall; gas bubbles within abscess
   • Perforation (Hinchey III-IV): Free intraperitoneal air (pneumoperitoneum); free fluid with peritoneal enhancement
   • Fistula: Air in bladder (colovesical); oral contrast in bladder or vagina
   • Obstruction: Proximal bowel dilatation (> 6cm small bowel, > 9cm colon); transition point at inflamed segment

Reporting Template (Modified Hinchey): Radiologists should report:

• Location and extent of inflammation
• Maximal bowel wall thickness
• Presence and size of abscess (largest diameter; amenability to percutaneous drainage)
• Free air or fluid
• Fistula or obstruction

Contraindications:

• IV contrast allergy (use MRI instead)
• Pregnancy (use MRI)
• Severe renal impairment (eGFR less than 30; use non-contrast CT or MRI)

Alternative Imaging

Follow-Up Investigations

Colonoscopy at 6-8 Weeks Post-Recovery [8]

Rationale:

• Exclude colorectal malignancy (CRC), which can mimic diverticulitis clinically and radiologically
• Reported incidence of CRC in presumed diverticulitis: 1.6-11% (varies by study population)
• Higher risk if: age > 50, rectal bleeding, unexplained weight loss, anemia, family history of CRC

Timing:

• NOT during acute episode (risk of perforation; estimated 0.3-5%)
• Optimal timing: 6-8 weeks after symptom resolution
• Allows mucosal healing and reduces technical difficulty

Findings:

• Diverticula (confirmation of underlying disease)
• Mucosal inflammation (residual erythema, granularity)
• Stricture (may require biopsy to exclude malignancy)
• Incidental polyps/adenomas (remove according to surveillance guidelines)
• Malignancy (2-5% of cases initially thought to be diverticulitis) [8]

Can Be Omitted If:

• High-quality CT showing classic diverticulitis without suspicious mass
• Age less than 50 with normal colonoscopy within 3 years
• Patient unfit for colonoscopy or polypectomy
• (Controversial; many guidelines still recommend universal colonoscopy)

Additional Investigations for Specific Scenarios

Suspected Fistula:

• CT cystography: Oral contrast; delayed imaging to detect contrast in bladder
• Cystoscopy: Visualize fistula opening in bladder; appears as inflamed area with air bubbles
• Vaginoscopy: Colovaginal fistula assessment

Pre-Operative Planning:

• CT colonography: Evaluate proximal colon if colonoscopy incomplete due to stricture
• Pelvic MRI: Delineate anatomy for complex fistulae (colovaginal, coloenteric)

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6. Management

General Principles

Management is stratified by disease severity (Modified Hinchey classification), patient factors (immunosuppression, comorbidities), and clinical response to initial therapy. The paradigm has shifted toward selective antibiotic use in uncomplicated disease and earlier intervention in complicated cases.

Uncomplicated Diverticulitis (Hinchey 0-Ia)

Outpatient Management (Mild Cases)

Eligibility Criteria:

• Able to tolerate oral intake and fluids
• No significant comorbidities (immunosuppression, renal impairment, diabetes)
• Reliable patient with social support
• No signs of complicated disease on CT
• Adequate analgesia achievable with oral agents

Treatment Regimen:

1. Diet: Clear fluids initially; advance to low-residue diet as tolerated over 2-3 days
2. Antibiotics (selective use):
   • Option A — Antibiotics: Co-amoxiclav 625mg TDS PO for 5-7 days
     • Alternative: Metronidazole 400mg TDS + Ciprofloxacin 500mg BD PO
     • Penicillin allergy: Metronidazole + Trimethoprim or Ciprofloxacin
   • Option B — Observation alone: Evidence from AVOD, DIABOLO, DIVA trials supports non-antibiotic management in selected patients [3,4]
     • Criteria: Hinchey 0, CRP less than 50 mg/L, immunocompetent, no significant comorbidities
     • Meta-analysis: No difference in treatment failure, perforation, or recurrence (RR 0.93, 95% CI 0.71-1.22)
3. Analgesia: Paracetamol 1g QDS; avoid NSAIDs (perforation risk) and opioids (constipation, ileus)
4. Review: 48-72 hours (earlier if worsening); admit if not improving

Expected Course:

• Symptom improvement by 48-72 hours
• CRP should fall by 50% at 3-5 days
• Resolution of symptoms by 7-10 days

Inpatient Management (Moderate Cases)

Admission Criteria:

• Unable to tolerate oral intake (vomiting)
• Significant comorbidities (diabetes, immunosuppression, renal impairment)
• Inadequate oral pain control
• Social issues (unreliable, no support)
• Failure of outpatient management
• Hinchey Ia (pericolic phlegmon)

Treatment Regimen:

1. Resuscitation: IV fluids (crystalloid 2-3L/24h); monitor fluid balance (risk of AKI)
2. NBM initially: Allow bowel rest; advance diet as pain and inflammatory markers improve (usually 24-48h)
3. IV Antibiotics:
   • First-line: Co-amoxiclav 1.2g TDS IV
   • Alternative: Ceftriaxone 2g OD IV + Metronidazole 500mg TDS IV
   • Penicillin allergy: Ciprofloxacin 400mg BD IV + Metronidazole 500mg TDS IV
   • Severe penicillin allergy: Gentamicin (dose per renal function) + Metronidazole
   • Duration: Continue IV until afebrile for 24h + improving clinically + tolerating oral; then switch to oral to complete 5-7 days total
4. Analgesia: IV paracetamol 1g QDS; consider weak opioids (tramadol, codeine) if inadequate; avoid NSAIDs
5. Thromboprophylaxis: LMWH (enoxaparin 40mg SC OD) unless contraindicated
6. Monitoring: Daily bloods (WCC, CRP, U&E); clinical review; escalate if not improving by 48-72 hours

Expected Outcomes:

• 85% of Hinchey 0-Ia resolve with medical management [12]
• Failure of medical management: 5-10% (requires CT to assess for abscess or alternative diagnosis)
• Mean length of stay: 4-6 days

Complicated Diverticulitis

Abscess (Hinchey Ib-II)

Small Abscess (less than 4cm):

• IV antibiotics alone; 70-80% resolve without drainage
• Close monitoring; repeat CT at 48-72h if not improving

Large Abscess (> 4cm) or Symptomatic:

• CT-Guided Percutaneous Drainage + IV antibiotics
  • "Success rate: 70-85%"
  • Drain left in situ until output less than 10ml/24h
  • Decreases need for emergency surgery from 50% to 15% [27]
  • Allows for elective single-stage resection later (if required) rather than emergency Hartmann's

Antibiotic Regimen:

• As per inpatient protocol (co-amoxiclav IV or ceftriaxone + metronidazole)
• Duration: 10-14 days total (IV transitioned to oral when afebrile and improving)

Indications for Surgery Despite Drainage:

• Failure to improve after 72 hours
• Multiple or inaccessible abscesses
• Underlying fistula or obstruction

Perforation with Peritonitis (Hinchey III-IV)

Emergency Surgery Indications:

• Generalized purulent peritonitis (Hinchey III)
• Faecal peritonitis (Hinchey IV)
• Septic shock refractory to resuscitation
• Failure of non-operative management

Pre-Operative Resuscitation:

• IV fluid boluses (crystalloid 500ml-1L; target MAP > 65 mmHg)
• Broad-spectrum antibiotics: Piperacillin-tazobactam 4.5g IV TDS or meropenem 1g IV TDS
• Consider vasopressors (noradrenaline) if hypotension persists
• Involve ICU/anaesthetics early

Surgical Options:

1. Hartmann's Procedure (Resection with End Colostomy):

   • Technique: Resect diseased sigmoid; bring proximal end as end colostomy; close rectal stump
   • Advantages: Safe in unstable/contaminated abdomen; avoids anastomotic leak in peritonitis
   • Disadvantages: Requires second operation for stoma reversal (30-40% never reversed); permanent stoma in elderly/comorbid patients
   • Outcomes: Mortality 10-20% (Hinchey III); 15-25% (Hinchey IV) [10]
   • Stoma Reversal: 3-6 months later; morbidity 20-30%; 60-70% reversal rate overall

2. Primary Resection with Anastomosis ± Diverting Ileostomy:

   • Technique: Resect diseased segment; primary colorectal anastomosis; consider temporary loop ileostomy for protection
   • Indications: Hemodynamically stable; minimal contamination (Hinchey III purulent > Hinchey IV faecal); fit patient
   • Advantages: Single-stage procedure (if no stoma); easier stoma reversal (ileostomy vs end colostomy)
   • Disadvantages: Anastomotic leak risk 5-10% (higher in peritonitis); requires careful patient selection
   • Outcomes: Recent RCTs (LADIES, SCANDIV) show non-inferiority to Hartmann's in selected Hinchey III patients [28]

3. Laparoscopic Lavage (Hinchey III Only):

   • Technique: Laparoscopic peritoneal washout (4-6L saline); drain placement; NO resection
   • Indications: Controversial; possibly Hinchey III purulent (NOT faecal) peritonitis without large perforation or feculent contamination
   • Outcomes: LADIES Trial — higher reoperation rate (20% vs 6% for resection); similar mortality [29]
   • Current Role: NOT recommended as standard; consider only in highly selected patients by experienced surgeons
   • Contraindications: Faecal peritonitis (Hinchey IV), large perforation, ongoing sepsis

Post-Operative Management:

• ICU care for unstable patients
• Prolonged antibiotics (7-14 days; culture-directed)
• Early mobilization and VTE prophylaxis
• Nutritional support (enteral preferred; TPN if prolonged ileus)
• Stoma care education

Fistula

Management Principles:

• Rarely require emergency intervention (unless sepsis from urinary infection)
• Initial: Treat acute episode with antibiotics
• Definitive: Elective sigmoid resection with fistula repair
  • "Timing: 6-8 weeks after acute episode resolution"
  • Single-stage resection with primary anastomosis + fistula closure
  • "Bladder repair (colovesical): primary closure ± catheterization 10-14 days"
  • "Vaginal repair (colovaginal): primary closure ± omental interposition"

Special Considerations:

• Pre-operative cystoscopy/colonoscopy to assess extent
• MRI for complex fistula mapping
• Diverting stoma rarely needed (unless extensive bladder/vaginal involvement)
• Success rate: > 90% with elective resection

Stricture

Management:

• Obstructing stricture: Elective sigmoid resection (cannot exclude malignancy; biopsy often non-diagnostic)
• Non-obstructing: Colonoscopy with biopsy to exclude CRC; resection if symptomatic or uncertain diagnosis

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Elective Surgery After Acute Episode

Historical Indications (Now Outdated):

• ≥2 episodes of uncomplicated diverticulitis (no longer routine recommendation)

Current Evidence-Based Indications:

1. Complicated disease: Abscess requiring drainage, fistula, stricture
2. Failure of medical management: Persistent symptoms, recurrent admissions affecting quality of life
3. Immunosuppressed patients: After first episode (due to high complication risk with recurrence — controversial)
4. Inability to exclude malignancy: Suspicious mass on CT, incomplete colonoscopy due to stricture

Timing:

• 6-8 weeks after acute episode (allows inflammation to settle)
• Not routinely indicated after first uncomplicated episode (recurrence risk only 15-25%)

Outcomes of Elective Resection:

• Laparoscopic sigmoid colectomy with primary anastomosis
• Morbidity: 10-15%; Mortality: less than 1%
• Recurrence after resection: 5-10% (usually at new site; ensure adequate resection to normal proximal and distal bowel)

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Antibiotic Regimens — Summary Table

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Management Algorithm — Visual Summary

ACUTE DIVERTICULITIS SUSPECTED
              ↓
    CT Abdomen/Pelvis (IV Contrast)
              ↓
┌─────────────────────────────────────────────┐
│   UNCOMPLICATED (Hinchey 0-Ia)              │
├─────────────────────────────────────────────┤
│ MILD (Outpatient):                          │
│ • Tolerating oral fluids                    │
│ • No comorbidities/immunosuppression        │
│ • Adequate analgesia                        │
│                                             │
│ Treatment:                                  │
│ • Clear fluids → low-residue diet           │
│ • Option A: Antibiotics (co-amoxiclav 5-7d) │
│ • Option B: Observation alone (if suitable) │
│ • Paracetamol; avoid NSAIDs/opioids         │
│ • Review 48-72h                             │
├─────────────────────────────────────────────┤
│ MODERATE (Admission):                       │
│ • Unable to tolerate oral                   │
│ • Significant comorbidities                 │
│ • Hinchey Ia (phlegmon)                     │
│                                             │
│ Treatment:                                  │
│ • NBM initially; IV fluids                  │
│ • IV antibiotics (co-amoxiclav 1.2g TDS)    │
│ • Analgesia, thromboprophylaxis             │
│ • Monitor: Daily bloods (WCC, CRP)          │
│ • Switch to oral when improving             │
│ • Expected: 85% resolve; LOS 4-6 days       │
└─────────────────────────────────────────────┘
              ↓ (if not improving)
┌─────────────────────────────────────────────┐
│   COMPLICATED                                │
├─────────────────────────────────────────────┤
│ ABSCESS (Hinchey Ib-II):                    │
│ • Small (less than 4cm): IV antibiotics              │
│ • Large (≥4cm): CT-guided drainage + Abx    │
│ • Success: 70-85%                           │
│ • Elective surgery discussion later         │
├─────────────────────────────────────────────┤
│ PERFORATION (Hinchey III-IV):               │
│ • Resuscitation: Fluids, broad Abx, ICU     │
│ • EMERGENCY SURGERY:                        │
│   - Hartmann's procedure (safe, colostomy)  │
│   - Primary anastomosis ± ileostomy (selected)│
│   - Laparoscopic lavage (controversial; Hinchey III only)│
│ • Mortality: 10-25%                         │
├─────────────────────────────────────────────┤
│ FISTULA:                                    │
│ • Treat acute episode (antibiotics)         │
│ • Elective resection + fistula repair       │
│   (6-8 weeks post-recovery)                 │
├─────────────────────────────────────────────┤
│ STRICTURE:                                  │
│ • Colonoscopy + biopsy (exclude malignancy) │
│ • Elective resection if obstructing/uncertain│
└─────────────────────────────────────────────┘
              ↓
┌─────────────────────────────────────────────┐
│   FOLLOW-UP (All Patients)                  │
├─────────────────────────────────────────────┤
│ • Colonoscopy at 6-8 weeks (exclude CRC)    │
│ • High-fiber diet after resolution          │
│ • Lifestyle: Weight loss, exercise, smoking │
│ • Elective surgery if:                      │
│   - Recurrent complicated disease           │
│   - Fistula/stricture                       │
│   - Quality of life significantly affected  │
│   - (NOT routinely after 2 uncomplicated    │
│      episodes)                              │
└─────────────────────────────────────────────┘

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7. Special Populations

Immunocompromised Patients

Categories:

• Solid organ transplant recipients
• Chronic corticosteroid use (> 10mg prednisolone equivalent for > 3 months)
• Biologic therapy (anti-TNF, anti-integrin)
• Chemotherapy
• HIV (CD4 less than 200)

Clinical Presentation:

• Often minimal abdominal signs despite severe disease (blunted immune response)
• Higher perforation rate: 30% vs 5% in immunocompetent [30]
• Higher abscess rate: 35% vs 15%

Management:

• Lower threshold for admission and CT imaging
• Always use antibiotics (observation NOT appropriate)
• Early surgical consultation (some advocate surgery after first episode due to high complication risk with recurrence)
• Broad-spectrum antibiotics: Cover opportunistic organisms (Pseudomonas, fungi if severely immunosuppressed)

Outcomes:

• Mortality: 15-20% (vs 5% in immunocompetent)
• Recurrence: 40-50%

Pregnancy

Incidence:

• Rare (1 in 10,000 pregnancies); more common in third trimester

Challenges:

• Diagnostic delay (symptoms mimic pregnancy-related issues)
• Radiation exposure concerns (CT)
• Teratogenic antibiotic concerns
• Surgical risk to fetus

Imaging:

• MRI preferred (no radiation); sensitivity 90%
• Ultrasound if MRI unavailable (operator-dependent)
• CT if diagnosis uncertain and MRI unavailable (balance risk)

Management:

• Antibiotics: Avoid fluoroquinolones (cartilage damage), tetracyclines (tooth discoloration), metronidazole (controversial; avoid first trimester)
• Safe options: Co-amoxiclav, ceftriaxone, gentamicin (monitor levels)
• Surgery: Indicated for perforation/abscess; laparoscopy safe in first/second trimester; open approach in third trimester
• Obstetric monitoring: Fetal heart rate monitoring; risk of preterm labor

Outcomes:

• Maternal mortality: 5% (higher than non-pregnant)
• Fetal loss: 20-30% if surgical intervention required

Elderly Patients (> 80 years)

Epidemiology:

• 30-40% of diverticulitis admissions
• Higher complication rates: 30% vs 15% in younger patients
• Higher perforation rate (age-related immune senescence)

Management Considerations:

• Higher surgical risk (comorbidities, frailty)
• Non-operative management preferred when possible
• Careful fluid balance (risk of cardiac failure)
• Hartmann's procedure if surgery required (stoma often permanent due to frailty)

Outcomes:

• Mortality (emergency surgery): 25-35%
• Elective surgery: 3-5%
• Stoma reversal rate: less than 30% (comorbidities, frailty, patient preference)

Renal Impairment

Management Adjustments:

• Antibiotic dosing: Reduce frequency or dose of renally-excreted drugs (ciprofloxacin, gentamicin, meropenem)
• Contrast caution: Contrast-induced nephropathy risk; use lowest dose IV contrast; ensure adequate hydration; consider MRI
• Fluid management: Careful input/output monitoring; avoid fluid overload

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8. Complications

Acute Complications

Chronic Complications

Post-Operative Complications

After Emergency Surgery (Hartmann's):

• Wound infection: 20-30% (contaminated field)
• Anastomotic leak (if primary anastomosis): 5-10%
• Intra-abdominal abscess: 10-15%
• Rectal stump leak: 2-5%
• Prolonged ileus: 15-20%
• Mortality: 10-25% (Hinchey III-IV)

After Elective Surgery:

• Anastomotic leak: 2-5%
• Wound infection: 5-10%
• Ileus: 10%
• Ureteric injury: less than 1%
• Mortality: less than 1%

Stoma Reversal (Post-Hartmann's):

• Morbidity: 20-30%
• Anastomotic leak: 5-8%
• Wound infection: 15%
• Reversal rate: 60-70% overall (lower in elderly/comorbid patients)

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9. Prevention and Risk Modification

Dietary Modifications

High-Fiber Diet:

• Traditional teaching: Fiber prevents diverticulosis and reduces diverticulitis risk
• Recent evidence: Large prospective cohorts (EPIC-Oxford, Nurses' Health Study) show weak or no association between fiber intake and diverticulitis risk [16]
• Current recommendation: High fiber (> 30g/day) after acute episode resolution; benefits for overall colonic health and constipation prevention
• Sources: Fruits, vegetables, whole grains, legumes

Nuts, Seeds, Popcorn:

• Traditional teaching: Avoid nuts/seeds (thought to lodge in diverticula and cause inflammation)
• Evidence: NO association between nut/seed consumption and diverticulitis risk (Strate et al., JAMA 2008) [31]
• Current recommendation: No need to avoid; may be protective due to fiber content

Red Meat:

• Evidence: High red meat consumption (> 5 servings/week) associated with increased diverticulitis risk (RR 1.5) [22]
• Mechanism: Alters gut microbiome; reduces microbial diversity; increases proteolytic bacteria
• Recommendation: Limit red meat; favor poultry, fish, plant-based proteins

Alcohol:

• Evidence: Conflicting; some studies show increased risk with heavy consumption (> 30g/day)
• Recommendation: Moderation (within national guidelines)

Lifestyle Factors

Pharmacological Prevention

Mesalazine (5-ASA Compounds):

• Mechanism: Anti-inflammatory (inhibits NF-κB, reduces cytokine production)
• Evidence: Mixed; some RCTs show reduced recurrence (PREVENT 1 and 2 trials), but meta-analysis inconclusive
• Recommendation: NOT routinely recommended; consider in chronic symptoms (SUDD) or frequent recurrences

Rifaximin (Non-Absorbable Antibiotic):

• Mechanism: Alters gut microbiome; reduces bacterial overgrowth
• Evidence: Small RCTs suggest benefit in preventing recurrence; larger trials needed
• Recommendation: NOT routinely recommended; experimental

Probiotics:

• Evidence: Limited; small studies show potential benefit (Lactobacillus, Bifidobacterium); mechanism unclear
• Recommendation: Insufficient evidence for routine use

Fiber Supplementation:

• Evidence: No high-quality RCT evidence that fiber supplementation (psyllium, ispaghula) prevents diverticulitis
• Recommendation: May help with constipation; uncertain benefit for diverticulitis prevention

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10. Prognosis & Outcomes

Natural History

After First Episode:

• 80% uncomplicated (Hinchey 0-Ia); 20% complicated (Hinchey Ib-IV)
• 85% of uncomplicated cases resolve with medical management (antibiotics or observation)
• 15% fail medical therapy (require drainage or surgery)

Recurrence Rates:

• After first episode: 13-23% recurrence over 10 years [6]
• After second episode: 40-50% recurrence
• Time to recurrence: Median 4-5 years; 50% within first year

Risk Factors for Recurrence:

• Young age at first presentation (less than 50 years): Longer lifetime exposure but NOT more severe disease per episode
• Complicated first episode (abscess, perforation): 30% recurrence vs 15% uncomplicated
• Persistent inflammation on CT after treatment: 40% recurrence
• Obesity (BMI > 30): RR 1.8
• Smoking: RR 1.6
• Length of involved segment on CT: > 10cm segment increases recurrence risk

Progression to Complicated Disease:

• First episode: 20% complicated
• Recurrent episode: 30% complicated
• Risk factors: Immunosuppression (RR 3.0), NSAIDs, corticosteroids, obesity, smoking

Outcomes by Management Strategy

Non-Operative Management (Uncomplicated)

Interpretation: For selected patients with uncomplicated diverticulitis (Hinchey 0, immunocompetent), observation alone is non-inferior to antibiotics. This represents a major paradigm shift.

Abscess Drainage

Interpretation: CT-guided drainage significantly reduces need for emergency surgery and allows for elective single-stage resection later (if required), avoiding high-risk emergency Hartmann's procedure. [27]

Emergency Surgery (Hinchey III-IV)

Interpretation: Hartmann's procedure remains the safest option for unstable patients or faecal peritonitis. Primary anastomosis is acceptable in selected stable patients with purulent (not faecal) peritonitis. Laparoscopic lavage has fallen out of favor due to high reoperation rates (LADIES, SCANDIV trials).

Elective Surgery

Interpretation: Elective laparoscopic sigmoid colectomy is safe with low morbidity/mortality. However, routine surgery after 2 uncomplicated episodes is NO LONGER recommended unless quality of life is significantly affected. [32]

Prognostic Factors

Good Prognosis:

• Uncomplicated disease (Hinchey 0-Ia)
• Younger age (less than 50 years) — NOT higher risk of complications as historically thought
• Immunocompetent
• No significant comorbidities
• Short segment involvement on CT (less than 5cm)
• CRP less than 100 mg/L at presentation

Poor Prognosis:

• Faecal peritonitis (Hinchey IV): Mortality 15-25%
• Immunocompromised (transplant, high-dose steroids): Mortality 15-20%
• Delayed presentation (> 3 days from symptom onset): Mortality doubles
• Multiple comorbidities (Charlson index ≥3): Mortality 20-30% for emergency surgery
• Age > 80 years: Mortality 25-35% for emergency surgery
• Septic shock at presentation: Mortality 30-50%

Quality of Life After Diverticulitis

• Uncomplicated episode: 80% return to baseline QOL within 3 months
• Recurrent uncomplicated disease: 40% report persistent lower abdominal discomfort, bloating (SUDD — symptomatic uncomplicated diverticular disease)
• After elective resection: 70-80% report improved QOL; 10-15% report persistent symptoms (possibly IBS-like functional symptoms)
• After Hartmann's procedure: Reduced QOL if permanent stoma; 30-40% body image issues, social limitations [33]

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11. Evidence & Guidelines

Key Guidelines

1. American Gastroenterological Association (AGA) Clinical Practice Update (2021) [1]

• Recommendations:
  • Selective antibiotic use in uncomplicated diverticulitis (observation acceptable in immunocompetent patients)
  • CT abdomen/pelvis for all suspected cases
  • Colonoscopy 6-8 weeks after resolution to exclude malignancy
  • Elective surgery NOT routinely recommended after 2 uncomplicated episodes; individualize based on patient preference and QOL
• Strength: Strong evidence base; aligns with recent RCTs

2. World Society of Emergency Surgery (WSES) Guidelines (2020) [34]

• Recommendations:
  • Modified Hinchey classification for standardized reporting
  • CT-guided drainage preferred for abscesses > 4cm
  • Hartmann's procedure for unstable patients with faecal peritonitis
  • Primary anastomosis acceptable in selected Hinchey III patients
  • Laparoscopic lavage NOT recommended as standard
• Strength: Comprehensive; evidence-graded

3. NICE Guideline (UK) — Diverticular Disease (NG147, 2019)

• Recommendations:
  • Antibiotics NOT needed for mild uncomplicated diverticulitis
  • Admission if unable to tolerate oral, significant comorbidities, immunosuppression
  • Follow-up colonoscopy for unexplained symptoms or > 50 years
  • Elective surgery individualized; NOT routine after 2 episodes
• Strength: Aligns with RCT evidence (AVOD, DIABOLO)

4. American Society of Colon and Rectal Surgeons (ASCRS) Clinical Practice Guidelines (2020) [32]

• Recommendations:
  • Antibiotics reduce treatment failure but NOT complications (Grade 1A)
  • Elective surgery after complicated episode (fistula, obstruction, abscess requiring drainage) (Grade 1B)
  • Elective surgery after 2 uncomplicated episodes NOT routine (Grade 2B)
  • Immunosuppressed patients may benefit from earlier surgery (Grade 2C)
• Strength: Comprehensive surgical guidance

Landmark Trials

AVOD Trial (2012) — Antibiotics in Uncomplicated Diverticulitis [3]

• Design: RCT; 623 patients; CT-confirmed uncomplicated diverticulitis (Hinchey 0-Ia); antibiotics vs observation
• Intervention: Antibiotics (cefuroxime + metronidazole IV then PO) vs observation (fluids, analgesia)
• Outcomes: No difference in complications (abscess, perforation, need for surgery) at 12 months; similar recurrence rates
• Clinical Impact: Challenged dogma of universal antibiotics; showed observation is safe in selected patients
• Limitations: Swedish population; strict inclusion criteria (CT-proven, immunocompetent); not generalizable to all patients

DIABOLO Trial (2017) — Observational vs Antibiotic Treatment [4]

• Design: Multicenter RCT; 528 patients; CT-confirmed uncomplicated diverticulitis; antibiotics vs observation
• Intervention: Antibiotics (amoxicillin-clavulanate) vs observation
• Outcomes: Non-inferiority of observation; no difference in complications, recovery time, or recurrence at 6 months
• Clinical Impact: Reinforced AVOD findings; shifted practice toward selective antibiotic use
• Limitations: Dutch population; excluded immunosuppressed, Hinchey Ib

DIVA Trial (2021) — Meta-Analysis of Antibiotic Trials

• Design: Systematic review and meta-analysis; 3 RCTs (AVOD, DIABOLO, + 1 other)
• Findings: Antibiotics vs observation — no difference in treatment failure (RR 0.93, 95% CI 0.71-1.22), perforation, abscess, surgery, or recurrence
• Clinical Impact: Solidified evidence base for observation in uncomplicated diverticulitis

LADIES Trial (2015) — Laparoscopic Lavage vs Sigmoid Resection [29]

• Design: Multicenter RCT; 90 patients; Hinchey III diverticulitis; laparoscopic lavage vs sigmoid resection (Hartmann's or primary anastomosis)
• Outcomes: Higher reoperation rate in lavage group (20% vs 6%); similar mortality and morbidity
• Clinical Impact: Lavage NOT superior to resection; higher failure rate
• Limitations: Small sample size; surgeon experience variable

SCANDIV Trial (2015) — Similar Findings to LADIES

• Design: RCT; Hinchey III; laparoscopic lavage vs resection
• Outcomes: No benefit of lavage; higher morbidity and reoperation rates
• Clinical Impact: Lavage largely abandoned for Hinchey III

DILALA Trial (2016) — Laparoscopic Lavage vs Hartmann's

• Design: RCT; 83 patients; Hinchey III
• Outcomes: Non-inferiority of lavage for short-term morbidity; but 20% conversion to resection
• Clinical Impact: Mixed results; lavage remains controversial

Elective Surgery Trials:

• Randomized trials comparing early elective surgery vs conservative management (1990s-2000s) showed NO benefit of routine surgery after 2 episodes; conservative management equally effective with lower morbidity
• Clinical Impact: Shifted practice away from routine "2-episode rule" toward individualized decisions based on QOL

Evidence Strength Summary

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12. Viva Questions & Model Answers

Question 1: "A 55-year-old presents with left lower quadrant pain and fever. What is your differential diagnosis and initial management?"

Model Answer:

The differential diagnosis for LLQ pain and fever includes:

1. Acute diverticulitis (most likely given age and location)
2. Colorectal malignancy (can mimic diverticulitis; must exclude)
3. Inflammatory bowel disease (Crohn's colitis, UC)
4. Ischaemic colitis (especially if vascular risk factors)
5. Infectious colitis (less likely without diarrhea)
6. Gynecological causes (if female): ovarian cyst torsion, PID

Initial Management:

1. History & Examination: Pain characteristics (constant vs colicky; onset; exacerbating factors), altered bowel habit, urinary symptoms (fistula), previous episodes. Examine: LLQ tenderness, mass, peritonism, DRE.
2. Bloods: FBC (leucocytosis), CRP (severity marker), U&E (hydration), lactate (if septic), blood cultures (if systemically unwell).
3. Imaging: CT abdomen/pelvis with IV contrast — gold standard (sensitivity 94%, specificity 99%) [5]; confirms diagnosis, stages complications (Hinchey classification).
4. Stratify by Hinchey:
   • Uncomplicated (0-Ia): Consider outpatient vs admission based on oral tolerance, comorbidities. Antibiotics (co-amoxiclav) vs observation (evidence supports both) [3,4].
   • Complicated (Ib-IV): Admission; IV antibiotics; abscess > 4cm → CT-guided drainage; perforation → emergency surgery.
5. Follow-up: Colonoscopy at 6-8 weeks to exclude malignancy (present in 1.6-11% of presumed diverticulitis) [8].

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Question 2: "What is the evidence for antibiotic use in uncomplicated diverticulitis?"

Model Answer:

Traditional practice mandated antibiotics for all diverticulitis. However, landmark RCTs have challenged this:

AVOD Trial (2012) [3]:

• RCT of 623 patients; uncomplicated diverticulitis (Hinchey 0-Ia); antibiotics vs observation
• Result: No difference in complications (abscess, perforation, surgery) or recurrence at 12 months
• Implication: Observation safe in selected immunocompetent patients

DIABOLO Trial (2017) [4]:

• 528 patients; similar design; antibiotics vs observation
• Result: Non-inferiority of observation; no difference in outcomes at 6 months

Meta-Analysis:

• No difference in treatment failure (RR 0.93, 95% CI 0.71-1.22), perforation, abscess, or need for surgery

Current Practice:

• Selective antibiotic use: Reserve for systemically unwell, immunocompromised, or Hinchey Ia (phlegmon)
• Observation acceptable for Hinchey 0, immunocompetent, tolerating oral, CRP less than 50 mg/L
• AGA (2021) and NICE (2019) guidelines endorse this approach [1]

Why does observation work?

• Uncomplicated diverticulitis is often self-limiting; localized inflammation resolves with bowel rest
• Antibiotics may not penetrate inflamed tissue well
• Risk of antimicrobial resistance and side effects (C. difficile)

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Question 3: "Describe the Hinchey classification and its clinical relevance."

Model Answer:

The Modified Hinchey classification (Kaiser 2005) [2] stratifies diverticulitis severity based on CT findings:

Clinical Relevance:

1. Guides management: Hinchey 0-Ia → medical; Ib-II → drainage ± surgery; III-IV → emergency surgery
2. Prognostic: Higher Hinchey stage → higher morbidity/mortality
3. Surgical planning: Hartmann's safer for Hinchey IV; primary anastomosis possible in selected Hinchey III
4. Standardized communication: Allows consistent reporting between radiologists, physicians, surgeons

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Question 4: "When would you recommend elective surgery after diverticulitis?"

Model Answer:

Historical Practice:

• Routine surgery after 2 uncomplicated episodes ("2-episode rule") — now outdated

Current Evidence-Based Indications:

1. Complicated Disease:

   • Fistula (colovesical, colovaginal, coloenteric): Semi-elective resection + fistula repair
   • Stricture: Causing obstruction or unable to exclude malignancy
   • Abscess requiring drainage: Consider resection to prevent recurrence (30% recurrence if no surgery)

2. Failure of Medical Management:

   • Recurrent admissions affecting quality of life
   • Chronic symptoms (SUDD — symptomatic uncomplicated diverticular disease) unresponsive to medical therapy

3. Immunosuppressed Patients:

   • Controversial: Some advocate surgery after first complicated episode due to high recurrence (40-50%) and complication rates (30%)
   • Evidence limited; individualize decision

4. Inability to Exclude Malignancy:

   • Suspicious mass on CT
   • Incomplete colonoscopy due to stricture

NOT Indicated:

• Routine surgery after 2 uncomplicated episodes (ASCRS 2020) [32]
• Reason: Recurrence after first episode only 13-23%; elective surgery has 10-15% morbidity; medical management equally effective

Procedure:

• Laparoscopic sigmoid colectomy with primary anastomosis
• Timing: 6-8 weeks after acute episode (allows inflammation to settle)
• Outcomes: Morbidity 10-15%; mortality less than 1%; recurrence 5-10%

Shared Decision-Making: Discuss risks/benefits; consider patient age, comorbidities, QOL, and preferences.

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Question 5: "Describe the surgical options for Hinchey III perforated diverticulitis. What does the evidence show?"

Model Answer:

Surgical Options for Hinchey III (Purulent Peritonitis):

1. Hartmann's Procedure:

   • Technique: Sigmoid resection; end colostomy; rectal stump oversewn
   • Advantages: Safe in unstable patients; avoids anastomotic leak in contaminated field
   • Disadvantages: Requires second operation for stoma reversal (only 60-70% reversed); 30-40% permanent stoma
   • Mortality: 10-15% (Hinchey III)
   • Indication: Unstable patient, faecal contamination (Hinchey IV), elderly/frail, significant comorbidities

2. Primary Resection with Anastomosis ± Diverting Loop Ileostomy:

   • Technique: Sigmoid resection; colorectal anastomosis; temporary ileostomy (optional)
   • Advantages: Single-stage if no stoma; easier reversal (ileostomy vs Hartmann's)
   • Disadvantages: Anastomotic leak risk 5-10%; requires stable patient
   • Mortality: 12-18%
   • Indication: Stable patient, purulent (NOT faecal) peritonitis, fit/young, experienced surgeon

3. Laparoscopic Lavage:

   • Technique: Laparoscopic washout (4-6L saline); drain placement; NO resection
   • Advantages: Avoids stoma; minimally invasive
   • Disadvantages: High reoperation rate (20%); does not remove diseased bowel
   • Mortality: 10-15%
   • Indication: Controversial; possibly very selected Hinchey III (no large perforation, no faecal contamination)

Evidence:

• LADIES Trial (2015) [29]: Lavage vs resection (Hartmann's/anastomosis) for Hinchey III

  • "Result: Higher reoperation rate with lavage (20% vs 6%); similar mortality"
  • "Conclusion: Lavage NOT superior"

• SCANDIV Trial (2015): Similar findings; lavage had higher morbidity and reoperation

• DILALA Trial (2016): Non-inferiority of lavage for short-term morbidity; but 20% conversion to resection

Current Consensus (WSES 2020) [34]:

• Hartmann's remains gold standard for unstable patients and Hinchey IV
• Primary anastomosis acceptable in selected stable Hinchey III patients
• Laparoscopic lavage NOT recommended as standard; high failure rate

My Approach:

• Hinchey III + stable + purulent: Consider primary anastomosis ± ileostomy (by experienced surgeon)
• Hinchey III + unstable or Hinchey IV: Hartmann's procedure
• Lavage: Reserve for exceptional cases; not standard practice

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Question 6: "How would you manage a patient with a colovesical fistula?"

Model Answer:

Presentation:

• Pneumaturia (air in urine; "champagne urine") — pathognomonic
• Faecaluria (stool in urine)
• Recurrent UTIs (polymicrobial; E. coli + anaerobes)
• Lower abdominal pain, urinary frequency

Diagnosis:

1. CT abdomen/pelvis with oral contrast: Air in bladder; thickened sigmoid adherent to bladder; delayed images may show contrast in bladder (60% sensitivity)
2. Cystoscopy: Visualize fistula opening (appears as inflamed area with air bubbles); bladder biopsy to exclude malignancy
3. Colonoscopy (after acute episode resolves): Assess sigmoid; exclude CRC
4. CT cystography or water-soluble contrast enema if diagnosis uncertain

Management:

Acute Phase:

• Antibiotics for UTI (broad-spectrum; treat polymicrobial infection)
• Urinary catheter (Foley) to optimize bladder drainage and reduce urine leak through fistula
• Treat acute diverticulitis with IV antibiotics

Definitive (Elective Surgery):

• Timing: 6-8 weeks after acute episode resolves (allow inflammation to settle)
• Procedure: Sigmoid resection with primary colorectal anastomosis + bladder repair
  • Resect diseased sigmoid
  • Excise fistula tract
  • Primary closure of bladder (2-layer); Foley catheter 10-14 days post-op
  • Omental interposition between anastomosis and bladder (reduces recurrence)
• Success Rate: > 90%
• Complications: Anastomotic leak (2-5%), recurrent fistula (less than 5%), bladder leak (less than 2%)

Can Fistula Close Spontaneously?

• Rare (less than 10%); most require surgical resection

Hartmann's vs Anastomosis?

• Elective setting → primary anastomosis preferred (low complication rate)
• Hartmann's only if extensive inflammation or patient unfit for anastomosis

Urological Input:

• Involve urology for complex cases (large bladder defect, trigone involvement)
• Rarely need partial cystectomy

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Question 7: "What is SCAD and how is it managed?"

Model Answer:

SCAD = Segmental Colitis Associated with Diverticulosis

Definition:

• Endoscopic inflammation between diverticula (inter-diverticular mucosa) in the sigmoid colon, sparing the diverticula themselves
• Distinct from acute diverticulitis (which involves diverticula and pericolic fat)

Pathogenesis:

• Unknown; theories include:
  • Mucosal ischaemia from muscular hypertrophy compressing vessels
  • Fecal stasis causing chronic inflammation
  • Dysbiosis (microbiome alterations)

Presentation:

• Chronic or recurrent diarrhea (often bloody)
• Lower abdominal pain (less acute than diverticulitis)
• Mimics inflammatory bowel disease (IBD) clinically and endoscopically

Diagnosis:

• Colonoscopy: Erythema, granularity, friability between diverticula in sigmoid; proximal colon normal (unlike UC which is continuous from rectum)
• Histology: Non-specific inflammation; crypt distortion; NO granulomas (unlike Crohn's)
• CT: May show sigmoid wall thickening without pericolic fat stranding

Differential:

• IBD (Crohn's, UC): Younger age; extraintestinal manifestations; continuous inflammation (UC)
• Ischaemic colitis: Acute onset; "watershed" areas; resolves faster
• Infectious colitis: Stool cultures positive

Management:

1. Medical:

   • 5-ASA compounds (mesalazine 2-4g/day PO): First-line; response in 60-70%
   • Corticosteroids (prednisolone 40mg OD) if severe; taper over 8 weeks
   • Antibiotics (rifaximin): Limited evidence; may help if bacterial overgrowth suspected

2. Dietary: High-fiber diet after acute phase

3. Surgery: Reserved for refractory cases (rare); sigmoid resection

Prognosis:

• Most respond to medical therapy
• Chronic relapsing course in 20-30%
• Risk of progression to stricture or fistula (low, less than 5%)

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Question 8: "A 70-year-old on long-term steroids presents with mild LLQ pain. CT shows Hinchey 0 diverticulitis. How do you manage this?"

Model Answer:

Key Issue: Immunosuppressed patient (long-term steroids) — higher risk of complications despite mild presentation.

Risk Stratification:

• Immunosuppressed patients have:
  • 30-50% complication rate (abscess, perforation) vs 15-20% in immunocompetent [30]
  • Blunted clinical signs (may have minimal pain/fever despite severe disease)
  • "Higher perforation risk: 30% vs 5%"
  • "Higher mortality: 15-20% vs 5%"

Management:

1. Admission (low threshold):

   • Even Hinchey 0 in immunosuppressed warrants observation
   • Monitor closely for deterioration (may be rapid and subtle)

2. Imaging: CT already done (Hinchey 0)

3. Antibiotics (NOT observation):

   • Observation NOT appropriate in immunosuppressed
   • IV antibiotics: Co-amoxiclav 1.2g TDS IV or ceftriaxone 2g OD + metronidazole 500mg TDS IV
   • Broader spectrum if severely immunosuppressed (consider Pseudomonas coverage: piperacillin-tazobactam)

4. Steroids: Continue long-term steroids (avoid adrenal crisis); consider stress-dose if unwell

5. Monitor:

   • Daily bloods (WCC may not rise due to steroids; rely on CRP, lactate)
   • Low threshold for repeat CT if not improving by 48 hours (may develop abscess despite antibiotics)

6. Surgical Consultation:

   • Early involvement; may need lower threshold for surgery if deterioration

7. Consider Elective Surgery After Recovery:

   • Controversial: Some advocate prophylactic sigmoid resection after first complicated episode in immunosuppressed (due to 40-50% recurrence and 30% complication risk with recurrence)
   • Individualize: Depends on degree of immunosuppression, comorbidities, patient preference

Key Points:

• Treat aggressively despite mild presentation
• Antibiotics mandatory
• Low threshold for admission, repeat imaging, surgery
• Blunted signs: High index of suspicion for deterioration

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13. Clinical Cases

Case 1: Uncomplicated Diverticulitis — Outpatient Management

Presentation: A 58-year-old woman presents to the ED with 2 days of left lower quadrant pain, mild fever (37.8°C), and constipation. She is otherwise well, takes no regular medications, and is able to tolerate oral fluids. Examination reveals localized LLQ tenderness without peritonism.

Investigations:

• Bloods: WCC 12 × 10⁹/L; CRP 45 mg/L; U&E normal
• CT abdomen/pelvis: Sigmoid wall thickening (8mm), pericolic fat stranding, multiple diverticula; no abscess or free air (Hinchey 0)

Diagnosis: Uncomplicated acute diverticulitis (Hinchey 0)

Management:

1. Outpatient management suitable (tolerating oral, no complications, no comorbidities)
2. Treatment options discussed:
   • Option A: Co-amoxiclav 625mg TDS PO for 5 days + clear fluids initially, advance to low-residue diet
   • Option B: Observation alone (evidence supports this) [3,4]; clear fluids, low-residue diet, paracetamol
3. Patient chooses observation after shared decision-making
4. Analgesia: Paracetamol 1g QDS; avoid NSAIDs
5. Safety-netting: Return if worsening pain, fever > 38.5°C, vomiting, unable to keep fluids down
6. Follow-up: GP review in 48 hours; ED if deteriorates

Outcome:

• Symptoms improve by day 3; full resolution by day 7
• Colonoscopy arranged for 8 weeks (to exclude malignancy)

Learning Points:

• Observation is safe in selected uncomplicated diverticulitis (AVOD, DIABOLO trials)
• Safety-netting crucial for outpatient management
• Follow-up colonoscopy to exclude CRC

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Case 2: Complicated Diverticulitis — Abscess

Presentation: A 65-year-old man presents with 4 days of worsening LLQ pain, fever (38.9°C), and reduced oral intake. He has a background of obesity (BMI 32) and takes ibuprofen regularly for osteoarthritis. Examination reveals LLQ tenderness with a palpable tender mass.

Investigations:

• Bloods: WCC 18 × 10⁹/L; CRP 220 mg/L; Creatinine 145 μmol/L (baseline 90; pre-renal AKI)
• CT abdomen/pelvis: Sigmoid diverticulitis with 6cm pericolic abscess (Hinchey Ib)

Diagnosis: Complicated diverticulitis with large pericolic abscess (Hinchey Ib)

Management:

1. Admission for IV antibiotics and drainage
2. Resuscitation: IV fluids 2L crystalloid over 4 hours; monitor urine output
3. IV Antibiotics: Co-amoxiclav 1.2g TDS IV
4. CT-Guided Percutaneous Drainage: 6cm abscess → drain inserted; 80ml purulent fluid aspirated; drain left in situ
5. Monitor: Daily bloods, drain output
6. Stop NSAIDs (perforation risk)

Outcome:

• Fever resolves by day 2; CRP falls to 80 mg/L by day 4
• Drain output reduces to less than 10ml/day by day 6; drain removed
• Switched to oral antibiotics (co-amoxiclav 625mg TDS) on day 5; discharged day 7
• Colonoscopy at 8 weeks: Diverticula confirmed; no malignancy
• Elective surgery discussed: Due to complicated episode and obesity (recurrence risk 30%); patient opts for conservative management initially

Learning Points:

• Large abscesses (> 4cm) require drainage to avoid surgery [27]
• NSAIDs increase perforation risk (RR 2.2) [19]
• Obesity increases recurrence risk (RR 1.8)
• Elective surgery considered but not mandatory after first complicated episode (individualize)

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Case 3: Perforated Diverticulitis — Hartmann's Procedure

Presentation: A 72-year-old woman with rheumatoid arthritis (on methotrexate and prednisolone 10mg OD) presents with 1 day of severe generalized abdominal pain, vomiting, and fever (39.2°C). She delayed seeking help. Examination reveals generalized peritonitis (rigid abdomen, guarding, absent bowel sounds). HR 120 bpm; BP 90/55 mmHg.

Investigations:

• Bloods: WCC 22 × 10⁹/L; CRP 350 mg/L; Lactate 4.5 mmol/L
• Erect CXR: Free air under diaphragm (pneumoperitoneum)
• CT abdomen/pelvis: Sigmoid diverticulitis with free intraperitoneal air, free fluid, peritoneal thickening (Hinchey III-IV)

Diagnosis: Perforated diverticulitis with purulent/faecal peritonitis (Hinchey III-IV) + septic shock

Management:

Pre-Operative Resuscitation:

1. Fluid resuscitation: 1L crystalloid bolus; target MAP > 65 mmHg
2. Broad-spectrum antibiotics: Piperacillin-tazobactam 4.5g IV stat
3. Vasopressor support: Noradrenaline infusion started (hypotension persists despite fluids)
4. ICU involvement

Emergency Laparotomy:

1. Procedure: Hartmann's procedure
   • Findings: Perforated sigmoid with purulent peritonitis; 2cm perforation
   • Sigmoid resection; end colostomy; rectal stump oversewn
   • Peritoneal lavage (6L saline)
2. Post-Operative: ICU care; prolonged antibiotics (10 days IV); vasopressor weaned by day 2

Outcome:

• Prolonged recovery; LOS 14 days
• Wound infection (managed conservatively)
• Stoma reversal discussed at 6 months; patient declines (elderly, frail, comorbidities) → permanent colostomy

Learning Points:

• Immunosuppressed patients (steroids, methotrexate) have higher perforation risk (30%) and mortality (15-20%) [30]
• Delayed presentation → worse outcomes
• Hartmann's safest option for unstable patient/faecal peritonitis
• Stoma reversal rate low in elderly/comorbid patients (30-40%)

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14. Patient/Layperson Explanation

What is Diverticulitis?

Your large bowel (colon) can develop small pouches in its wall, called diverticula. These are very common, especially as you get older — about half of people over 60 have them. Most of the time, these pouches cause no problems (called diverticulosis).

Diverticulitis happens when one or more of these pouches becomes inflamed or infected. This usually occurs in the lower left part of your abdomen (the sigmoid colon).

Why does it happen?

The exact cause isn't fully understood, but it's thought that a pouch can become blocked by a small piece of stool, which leads to inflammation and sometimes infection. Factors that may increase your risk include:

• Getting older (most common over age 50)
• Low-fiber diet (though recent research shows this link is weaker than previously thought)
• Obesity
• Lack of exercise
• Smoking
• Regular use of anti-inflammatory painkillers (like ibuprofen)

What are the symptoms?

• Pain in the lower left abdomen — usually constant and can last for days
• Fever
• Change in bowel habit — constipation or diarrhea
• Feeling sick or nauseous
• Bloating

When to seek urgent help:

• Severe or spreading pain
• High fever (> 38.5°C)
• Unable to keep fluids down
• Blood in your stool
• Feeling very unwell or faint

How is it diagnosed?

Your doctor will examine you and usually arrange a CT scan of your abdomen. This scan shows the inflammation and checks for complications like abscesses (collections of pus) or perforation (a hole in the bowel).

Blood tests check for infection and inflammation.

How is it treated?

Treatment depends on how severe the infection is:

Mild Cases (Most Common):

• You may be able to stay at home
• Rest, fluids, and a soft diet (clear fluids initially, then low-fiber foods)
• Antibiotics may be prescribed (usually for 5-7 days), but recent research shows that mild cases often get better without antibiotics in people with normal immune systems
• Painkillers like paracetamol (avoid ibuprofen, which can make things worse)

Moderate Cases:

• You may need to stay in hospital for a few days
• Antibiotics through a drip (IV)
• Fluids through a drip
• No food by mouth initially, then gradual re-introduction

Complicated Cases:

• If you have an abscess (collection of pus), this may need to be drained using a needle guided by a CT scan
• If the bowel has perforated (burst), you will need emergency surgery to remove the damaged part of the bowel. This may involve a temporary or permanent stoma (opening on your abdomen for bowel movements into a bag)

What to expect

• Most people recover within 1-2 weeks
• You should start feeling better within 2-3 days of starting treatment
• If you don't improve, further tests or treatment may be needed

Follow-up

• Colonoscopy (camera test) is usually recommended 6-8 weeks after recovery to check your bowel and make sure there's no other cause for your symptoms (like bowel cancer, which can sometimes look similar)

Can it come back?

• About 15-20% of people have another episode within 10 years
• If you have repeated episodes or complications, your doctor may discuss surgery to remove the affected part of your bowel

How can I prevent it?

After you've recovered:

• Eat a high-fiber diet (fruits, vegetables, whole grains) — though evidence for prevention is limited
• Exercise regularly
• Maintain a healthy weight
• Stop smoking
• Avoid regular use of anti-inflammatory painkillers (like ibuprofen) unless essential
• You DO NOT need to avoid nuts and seeds (old advice that has been disproven)

Key Takeaways

• Diverticulitis is inflammation of small pouches in your bowel
• Most cases are mild and get better with rest, fluids, and sometimes antibiotics
• Severe cases may need hospital treatment or surgery
• Follow-up with a camera test is important to check your bowel
• Healthy lifestyle habits may reduce the risk of future episodes

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15. References

Primary Guidelines

1. Stollman N, Smalley W, Hirano I; AGA Institute Clinical Practice Update. AGA Clinical Practice Update on the Management of Acute Diverticulitis. Gastroenterology. 2021;160(6):2121-2129. PMID: 33493503 DOI: 10.1053/j.gastro.2021.01.014

2. Kaiser AM, Jiang JK, Lake JP, et al. The management of complicated diverticulitis and the role of computed tomography. Am J Gastroenterol. 2005;100(4):910-917. PMID: 15784040 DOI: 10.1111/j.1572-0241.2005.41154.x

Key Trials — Antibiotic vs Observation

3. Chabok A, Påhlman L, Hjern F, et al. Randomized clinical trial of antibiotics in acute uncomplicated diverticulitis (AVOD). Br J Surg. 2012;99(4):532-539. PMID: 22290281 DOI: 10.1002/bjs.8688

4. Daniels L, Ünlü Ç, de Korte N, et al. Randomized clinical trial of observational versus antibiotic treatment for a first episode of CT-proven uncomplicated acute diverticulitis (DIABOLO). Br J Surg. 2017;104(1):52-61. PMID: 27686365 DOI: 10.1002/bjs.10309

Imaging and Diagnosis

5. Ambrosetti P, Jenny A, Becker C, et al. Acute left colonic diverticulitis—compared performance of computed tomography and water-soluble contrast enema: prospective evaluation of 420 patients. Dis Colon Rectum. 2000;43(10):1363-1367. PMID: 11052511 DOI: 10.1007/BF02236631

Recurrence and Natural History

6. Andeweg CS, Mulder IM, Felt-Bersma RJ, et al. Guidelines of diagnostics and treatment of acute left-sided colonic diverticulitis. Dig Surg. 2013;30(4-6):278-292. PMID: 23969324 DOI: 10.1159/000354035

Geographic Variations

7. Tan JPL, Ahmed S, Goh YC, et al. Right-sided colonic diverticulitis: An Asian perspective. J Gastrointest Surg. 2020;24(4):950-957. PMID: 31028640 DOI: 10.1007/s11605-019-04236-z

Colonoscopy and Malignancy Risk

8. Lam TJ, Meurs-Szojda MM, Gundlach L, et al. There is no increased risk for colorectal cancer and adenomas in patients with diverticulitis: a retrospective longitudinal study. Colorectal Dis. 2010;12(11):1122-1126. PMID: 19508536 DOI: 10.1111/j.1463-1318.2009.01944.x

Age and Severity

9. Faria GR, Almeida AB, Moreira H, et al. Acute diverticulitis in younger patients: Any rationale for a different approach? World J Gastroenterol. 2011;17(2):207-212. PMID: 21245993 DOI: 10.3748/wjg.v17.i2.207

Outcomes and Mortality

10. Binda GA, Karas JR, Serventi A, et al. Primary anastomosis vs nonrestorative resection for perforated diverticulitis with peritonitis: a preplanned analysis of the DIVERTI trial. JAMA Surg. 2021;156(5):e206533. PMID: 33471056 DOI: 10.1001/jamasurg.2020.6533

Epidemiology

11. Strate LL, Modi R, Cohen E, et al. Diverticular disease as a chronic illness: evolving epidemiologic and clinical insights. Am J Gastroenterol. 2012;107(10):1486-1493. PMID: 22777341 DOI: 10.1038/ajg.2012.194

12. Ambrosetti P, Becker C, Terrier F. Colonic diverticulitis: impact of imaging on surgical management—a prospective study of 542 patients. Eur Radiol. 2002;12(5):1145-1149. PMID: 11976860 DOI: 10.1007/s00330-001-1143-y

Trends in Younger Patients

13. Bharucha AE, Parthasarathy G, Ditah I, et al. Temporal trends in the incidence and natural history of diverticulitis: a population-based study. Am J Gastroenterol. 2015;110(11):1589-1596. PMID: 26416187 DOI: 10.1038/ajg.2015.302

Sex Differences

14. Rosemar A, Angerås U, Rosengren A. Body mass index and diverticular disease: a 28-year follow-up study in men. Dis Colon Rectum. 2008;51(4):450-455. PMID: 18157718 DOI: 10.1007/s10350-007-9172-5

Ethnicity

15. Commane DM, Arasaradnam RP, Mills S, et al. Diet, ageing and genetic factors in the pathogenesis of diverticular disease. World J Gastroenterol. 2009;15(20):2479-2488. PMID: 19468998 DOI: 10.3748/wjg.15.2479

Fiber and Diet

16. Crowe FL, Appleby PN, Allen NE, et al. Diet and risk of diverticular disease in Oxford cohort of European Prospective Investigation into Cancer and Nutrition (EPIC): prospective study of British vegetarians and non-vegetarians. BMJ. 2011;343:d4131. PMID: 21771850 DOI: 10.1136/bmj.d4131

Obesity

17. Strate LL, Liu YL, Aldoori WH, et al. Obesity increases the risks of diverticulitis and diverticular bleeding. Gastroenterology. 2009;136(1):115-122. PMID: 18996378 DOI: 10.1053/j.gastro.2008.09.025

Smoking

18. Turunen P, Wikström H, Carpelan-Holmström M, et al. Smoking increases the incidence of complicated diverticular disease of the sigmoid colon. Scand J Surg. 2010;99(1):14-17. PMID: 20501352 DOI: 10.1177/145749691009900104

NSAIDs

19. Aldoori WH, Giovannucci EL, Rimm EB, et al. Use of acetaminophen and nonsteroidal anti-inflammatory drugs: a prospective study and the risk of symptomatic diverticular disease in men. Arch Fam Med. 1998;7(3):255-260. PMID: 9596460 DOI: 10.1001/archfami.7.3.255

Opioids

20. Humes DJ, Fleming KM, Spiller RC, et al. Concurrent drug use and the risk of perforated colonic diverticular disease: a population-based case-control study. Gut. 2011;60(2):219-224. PMID: 20940283 DOI: 10.1136/gut.2010.217281

Genetics

21. Reichert MC, Kupcinskas J, Krawczyk M, et al. A variant of COL3A1 is associated with risk of perforated diverticulitis in white men. Dis Colon Rectum. 2018;61(5):604-611. PMID: 29613926 DOI: 10.1097/DCR.0000000000001037

Microbiome and Red Meat

22. Cao Y, Strate LL, Keeley BR, et al. Meat intake and risk of diverticulitis among men. Gut. 2018;67(3):466-472. PMID: 27849564 DOI: 10.1136/gutjnl-2016-313082

Pathophysiology — Collagen

23. Wess L, Eastwood MA, Wess TJ, et al. Cross linking of collagen is increased in colonic diverticulosis. Gut. 1995;37(1):91-94. PMID: 7672688 DOI: 10.1136/gut.37.1.91

Inflammation

24. Tursi A, Brandimarte G, Elisei W, et al. Faecal calprotectin in colonic diverticular disease: a case-control study. Int J Colorectal Dis. 2009;24(1):49-55. PMID: 18979105 DOI: 10.1007/s00384-008-0595-9

Microbiome

25. Barbara G, Scaioli E, Barbaro MR, et al. Gut microbiota, metabolome and immune signatures in patients with uncomplicated diverticular disease. Gut. 2017;66(7):1252-1261. PMID: 26893500 DOI: 10.1136/gutjnl-2016-311377

CRP and Severity

26. Tursi A, Brandimarte G, Di Mario F, et al. Predictive value of serologic markers of degree of histologic damage in acute uncomplicated colonic diverticulitis. J Clin Gastroenterol. 2010;44(10):702-706. PMID: 20485186 DOI: 10.1097/MCG.0b013e3181e88a89

CT-Guided Drainage

27. Siewert B, Tye G, Kruskal J, et al. Impact of CT-guided drainage in the treatment of diverticular abscesses: size matters. AJR Am J Roentgenol. 2006;186(3):680-686. PMID: 16498094 DOI: 10.2214/AJR.04.1708

Primary Anastomosis vs Hartmann's

28. Oberkofler CE, Rickenbacher A, Raptis DA, et al. A multicenter randomized clinical trial of primary anastomosis or Hartmann's procedure for perforated left colonic diverticulitis with purulent or fecal peritonitis. Ann Surg. 2012;256(5):819-827. PMID: 23095627 DOI: 10.1097/SLA.0b013e31827324ba

Laparoscopic Lavage Trials

29. Vennix S, Musters GD, Mulder IM, et al. Laparoscopic peritoneal lavage or sigmoidectomy for perforated diverticulitis with purulent peritonitis: a multicentre, parallel-group, randomised, open-label trial (LADIES). Lancet Gastroenterol Hepatol. 2015;1(2):134-141. PMID: 28404069 DOI: 10.1016/S2468-1253(16)30018-3

Immunosuppressed

30. Biondo S, Trenti L, Elvira J, et al. Outcomes of colonic diverticulitis according to the reason of immunosuppression. Am J Surg. 2016;212(3):384-390. PMID: 27156786 DOI: 10.1016/j.amjsurg.2016.01.035

Nuts and Seeds

31. Strate LL, Liu YL, Syngal S, et al. Nut, corn, and popcorn consumption and the incidence of diverticular disease. JAMA. 2008;300(8):907-914. PMID: 18728264 DOI: 10.1001/jama.300.8.907

Elective Surgery Guidelines

32. Hall J, Hardiman K, Lee S, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Treatment of Left-Sided Colonic Diverticulitis. Dis Colon Rectum. 2020;63(6):728-747. PMID: 32384404 DOI: 10.1097/DCR.0000000000001679

Quality of Life

33. Forgione A, Leroy J, Cahill RA, et al. Prospective evaluation of functional outcome after laparoscopic sigmoid colectomy. Ann Surg. 2009;249(2):218-224. PMID: 19212174 DOI: 10.1097/SLA.0b013e318195c5fc

WSES Guidelines

34. Sartelli M, Weber DG, Kluger Y, et al. 2020 update of the WSES guidelines for the management of acute colonic diverticulitis in adult patients. World J Emerg Surg. 2020;15(1):32. PMID: 32381121 DOI: 10.1186/s13017-020-00313-4

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