DIVERTICULITIS AND DIVERTICULAR DISEASE OF THE COLON
COMPREHENSIVE SCIENTIFIC REVIEW — PATHOPHYSIOLOGY, CLINICAL FEATURES, AND MANAGEMENT (2026 UPDATE)
1. PRECISE MEDICAL DEFINITION AND NOMENCLATURE
Diverticular disease = pathological spectrum including:
- Diverticulosis: anatomical presence of diverticula without inflammation
- Diverticulitis: inflammation ± infection of a diverticulum
- Complicated diverticulitis: abscess, perforation, fistula, obstruction, or peritonitis
Colonic diverticulum = sac-like herniation of mucosa and submucosa through defects in the muscular layer → acquired pseudodiverticulum (does not contain all bowel wall layers)
2. MICRO- AND MACROSCOPIC PATHOLOGIC ANATOMY
Diverticula arise at:
- vascular penetration points (vasa recta)
- muscular weak zones
- mesenteric border
Structural features
- typical diameter: 5–10 mm
- maximum: ≈2 cm
- predominant location: sigmoid colon (high intraluminal pressure zone)
3. GLOBAL EPIDEMIOLOGY
Prevalence increases with age:
| Age | Prevalence |
|---|---|
| <40 | <10% |
| >60 | ~50% |
| >80 | >65% |
Risk factors
- low-fiber diet
- visceral obesity
- sedentary lifestyle
- smoking
- chronic NSAID use
- altered gut microbiota
4. ADVANCED PATHOPHYSIOLOGY
4.1 FORMATION MECHANICS
Sigmoid colon generates high segmental pressures.
Laplace law
T = P × r
Where
T = wall tension
P = intraluminal pressure
r = radius
↑ segmental pressure → ↑ tension → mucosal herniation.
4.2 TRANSITION: DIVERTICULOSIS → DIVERTICULITIS
Accepted mechanism:
- fecal impaction in diverticular neck
- ostial obstruction
- bacterial proliferation
- local inflammation
- microperforation
Result:
- pericolonic inflammation
- phlegmon
- abscess
4.3 IMMUNE-INFLAMMATORY RESPONSE
Activated mediators:
- IL-6
- TNF-α
- C-reactive protein
- neutrophils
Severity depends on:
- perforation size
- bacterial load
- host immunity
5. CLINICAL PRESENTATION
5.1 NON-INFLAMED DIVERTICULOSIS
Often asymptomatic. When symptomatic:
- chronic LLQ pain
- bloating
- bowel habit change
Absent:
- fever
- leukocytosis
- elevated CRP
5.2 ACUTE DIVERTICULITIS
Classic triad:
- left lower quadrant pain
- fever
- leukocytosis
Additional findings:
- nausea
- constipation or diarrhea
- urinary irritation symptoms
- localized guarding
5.3 RED FLAGS
- peritoneal signs
- hypotension
- tachycardia
- elevated lactate
- confusion
- diffuse pain
→ suspect perforation or sepsis.
6. MODIFIED HINCHEY CLASSIFICATION
I — localized inflammation / small abscess
II — pelvic or retroperitoneal abscess
III — purulent peritonitis
IV — fecal peritonitis
7. DIAGNOSIS
GOLD STANDARD
Contrast-enhanced abdominopelvic CT
Diagnostic findings:
- bowel wall thickening >4 mm
- inflamed pericolic fat
- abscess
- free air
- free fluid
LAB FINDINGS
Typical:
- neutrophilic leukocytosis
- elevated CRP
- procalcitonin if complicated
Colonoscopy Contraindicated in acute phase → perforation risk.
8. COMPLICATIONS
- abscess
- perforation
- colovesical fistula
- obstruction
- lower GI bleeding
9. EVIDENCE-BASED MANAGEMENT
9.1 UNCOMPLICATED DIVERTICULITIS
Modern guidelines:
Antibiotics not routinely required
Indications:
- immunocompromised state
- sepsis
- severe comorbidity
- high fever
- markedly elevated CRP
Standard care:
- liquid diet initially
- analgesia
- hydration
- clinical monitoring
9.2 COMPLICATED DIVERTICULITIS
Requires:
- hospitalization
- IV antibiotics
- serial CT
- possible percutaneous drainage
9.3 SURGICAL INDICATIONS
Urgent if:
- peritonitis
- free perforation
- treatment failure
- sepsis
Procedures:
- sigmoid resection
- Hartmann procedure
- selected primary anastomosis
10. EMPIRIC ANTIBIOTIC REGIMENS
Coverage must include:
- Gram negatives
- anaerobes
Common regimens:
- ceftriaxone + metronidazole
- piperacillin–tazobactam
- amoxicillin–clavulanate
11. PROGNOSIS
Uncomplicated diverticulitis
Mortality <1%
Complicated with sepsis
Mortality up to 15%
Recurrence risk
20–35%
12. SECONDARY PREVENTION
Evidence-supported:
✔ high-fiber diet
✔ regular exercise
✔ visceral fat reduction
✔ avoid chronic NSAIDs
Not supported:
- avoiding seeds
- avoiding nuts
Current evidence shows no causal relationship.
13. COMMON CLINICAL ERRORS
Even experienced physicians may:
- prescribe antibiotics to all cases
- order colonoscopy during acute phase
- omit CT imaging
- underestimate mild pain in elderly patients
- misdiagnose as IBS
14. ADVANCED PATHOPHYSIOLOGICAL PERSPECTIVE
Diverticular disease is now considered:
multifactorial biomechanical + microbiomic + chronic inflammatory disorder
Active research areas:
- colonic dysbiosis
- neuromuscular dysfunction
- collagen defects of bowel wall
15. HIGH-LEVEL MEDICAL CONCLUSION
Diverticulitis is not merely infection of a colonic sac.
It is a dynamic process involving interaction among:
- intraluminal pressure
- wall architecture
- microbiota
- mucosal immunity
Modern management requires:
- risk stratification
- precise radiologic diagnosis
- individualized therapy
- avoidance of unnecessary antibiotics
CLINICAL MASTER STATEMENT
Diverticulitis is a segmental inflammatory condition of the colon secondary to diverticular microperforation whose severity depends more on the host inflammatory response than on diverticulum size.
Author Attribution:
DrRamonReyesMD — Scientific Clinical Edition 2026
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