Intestinal Obstruction

Gut Block Basics - Defining the Jam

Intestinal obstruction (IO) is the impairment of normal aboral passage of intestinal contents.

• By Pathophysiology:
  • Mechanical: Physical lumen blockage.
  • Functional (Ileus): Neuromuscular hypomotility.
• By Vascular Supply:
  • Simple: Lumen occluded, blood supply intact.
  • Strangulated: Lumen occluded + compromised blood supply.

    ⭐ Strangulated obstruction is a surgical emergency due to risk of bowel necrosis and perforation.

• By Onset:
  • Acute: Sudden onset.
  • Chronic: Gradual, insidious onset.
• By Location:
  • High: Duodenum, jejunum, proximal ileum.
  • Low: Distal ileum, colon.
• By Severity:
  • Partial: Incomplete obstruction.
  • Complete: Full obstruction.
• By Lumen Status:
  • Open Loop: Obstruction at one point.
  • Closed Loop: Segment obstructed at two points (e.g., volvulus); ↑ risk of strangulation.

The Usual Suspects - Obstruction Origins

Mechanical intestinal obstruction stems from diverse origins, often specific to the small or large bowel. Key causes include:

• Hernias
• Adhesions
• Volvulus
• Obstruction (e.g., gallstone, foreign body)
• Cancer / Crohn's disease

⭐ Post-operative adhesions are the most common cause of Small Bowel Obstruction (SBO) in adults worldwide.

Body's Backlash - Symptoms & Signs

• Pathophysiology:

  • Proximal bowel distension (gas & fluid accumulation)
  • Fluid & electrolyte sequestration (→ dehydration, shock)
  • ↑ Peristalsis initially, then ↓ (bowel fatigue)
  • Risk of ↑ intraluminal pressure → ischemia, necrosis, perforation

• Clinical Features: Cardinal Symptoms (📌 PVDC)

  • Pain: Colicky abdominal pain (initially); constant if ischemia
  • Vomiting: Nature varies with obstruction level
  • Distension: Abdominal distension
  • Constipation: Absolute constipation (no flatus/feces) or obstipation
  • Signs:
    • Altered bowel sounds: Hyperactive (early) → hypoactive/absent (late)
    • Abdominal tenderness (diffuse/localized)
    • Signs of dehydration: Tachycardia, hypotension, dry mucous membranes

⭐ The nature of vomitus can indicate the level of obstruction (e.g., non-bilious in pyloric, bilious in proximal SBO, feculent in distal SBO/LBO).

Spot & Solve - Dx & Rx Roadmap

• Diagnostic Modalities:
  • Abdominal X-ray (supine & erect):
    • Dilated bowel loops (small bowel >3 cm, large bowel >6 cm, cecum >9 cm - 📌 3-6-9 rule)
    • Multiple air-fluid levels (≥2, >2.5 cm wide)
    • String of pearls sign
    • Paucity of distal gas
  • CT scan (abdomen & pelvis, with contrast):
    • Confirms diagnosis; Identifies transition point, cause, severity.
    • Detects complications: ischemia, strangulation, perforation.

⭐ CT scan with contrast is the gold standard imaging modality for diagnosing intestinal obstruction, identifying the cause (e.g., adhesions, hernia, volvulus, intussusception, tumor), and detecting complications like strangulation.

• Management Algorithm:

High‑Yield Points - ⚡ Biggest Takeaways

• Adhesions: Most common cause of small bowel obstruction (SBO) in adults.
• Hernias: Second most common cause of SBO, particularly incarcerated hernias.
• Intussusception: Most common cause of intestinal obstruction in children (<2 years); associated with "currant jelly" stool.
• Volvulus: Sigmoid type is common in elderly, shows "coffee bean" sign on X-ray.
• Cardinal features: Colicky abdominal pain, vomiting, abdominal distension, absolute constipation.
• Strangulation: A life-threatening complication leading to bowel ischemia, necrosis, and perforation.
• Imaging: Abdominal X-ray reveals dilated bowel loops proximal to obstruction and multiple air-fluid levels.