Diverticular disease

Basics & Pathophysiology - Gut's Little Pockets

• Diverticulosis: Asymptomatic herniation of mucosa and submucosa through the muscularis propria, forming pseudodiverticula.
• Diverticulitis: Inflammation and potential microperforation of a diverticulum, often due to an obstructing fecalith.
• Pathophysiology: Chronic low-fiber diet and constipation ↑ intraluminal pressure. This forces outpouchings at weak points in the colonic wall, typically where the vasa recta penetrate the circular muscle layer.
• Location: Predominantly affects the sigmoid colon (~95%) due to its narrow diameter, which generates the highest wall tension per Laplace's law.

⭐ Most colonic diverticula are pseudodiverticula (false diverticula), lacking a muscularis externa layer. True diverticula, containing all gut wall layers, are rare (e.g., Meckel's diverticulum).

Presentation & Diagnosis - When Pockets Protest

• Asymptomatic Diverticulosis: The majority of cases. Usually an incidental finding during a colonoscopy performed for other reasons.
• Acute Diverticulitis Presentation:
  • Classic: Constant, aching LLQ pain (sigmoid colon is the most common site).
  • Associated: Low-grade fever, anorexia, nausea, and a change in bowel habits (constipation or diarrhea).
  • Physical Exam: Localized LLQ tenderness, guarding, and sometimes a palpable, tender mass.
• Diagnostic Gold Standard:
  • Abdominal/Pelvic CT scan with IV contrast is the preferred imaging test.
  • Key CT findings: Focal bowel wall thickening (>4 mm), pericolic fat stranding, abscess, or free air (perforation).
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  • ⚠️ Contraindicated in Acute Phase: Colonoscopy and barium enema due to high perforation risk. Perform 6-8 weeks post-resolution to rule out malignancy.

⭐ The most common fistula in diverticulitis is a colovesical fistula, presenting with pneumaturia (air in urine), fecaluria, and recurrent UTIs.

Management Algorithm - Calming the Colon

• Antibiotics: Cover gram-negatives & anaerobes (e.g., Ciprofloxacin + Metronidazole) for 7-10 days.
• Complicated Cases:
  • Abscess > 3 cm: Percutaneous drainage.
  • Perforation / Peritonitis: Emergent surgery (e.g., Hartmann's procedure).
• Post-Recovery: High-fiber diet to prevent recurrence. All patients need a follow-up colonoscopy to exclude malignancy.

⭐ After an initial episode of uncomplicated diverticulitis, colonoscopy is crucial to rule out an underlying colorectal cancer, which can present with a similar clinical and radiographic picture.

Complications - Danger Zones

• Abscess: Most common complication; suspect with persistent fever despite antibiotics.
• Fistula: Colovesical is classic → pneumaturia, fecaluria. Colovaginal also possible.
• Obstruction: Can cause large bowel obstruction from stricturing or edema.
• Perforation: Free air on imaging; high risk of sepsis.
• Bleeding (Painless): Abrupt, large-volume hematochezia.

⭐ While most diverticular bleeding stops spontaneously (>75%), colovesical fistula is the most common fistula type associated with diverticulitis.

• Diverticulosis is typically asymptomatic; diverticulitis is inflammation/infection of a diverticulum.
• Most common cause of painless lower GI bleeding in adults >60 years old.
• Acute diverticulitis presents with LLQ abdominal pain, fever, and leukocytosis.
• CT scan of the abdomen and pelvis is the best initial test for diagnosis.
• Colonoscopy is contraindicated during an acute episode due to perforation risk.
• Uncomplicated cases are treated with bowel rest and antibiotics.