Intestinal Obstruction

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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.

Types of Intestinal Obstruction

The Usual Suspects - Obstruction Origins

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

Causes of Bowel Obstructions Diagram

CategorySmall Bowel Obstruction (SBO) ExamplesLarge Bowel Obstruction (LBO) Examples
Primary CauseAdhesions (most common, typically post-surgical)Colorectal Cancer (most common malignant cause)
Other CausesHernias (external, internal), Volvulus, Intussusception (children), Gallstone ileus, Crohn's diseaseSigmoid/Cecal Volvulus, Diverticular Strictures, Fecal Impaction, Extrinsic Compression
  • 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.

Abdominal X-ray with air-fluid levels in small bowel

⭐ 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.

Practice Questions: Intestinal Obstruction

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Most common cause of acute intestinal obstruction in children is

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Flashcards: Intestinal Obstruction

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Histological pattern of neutrophils emanating from a crypt, reminiscent of a volcanic eruption is pathognomonic for _____

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Histological pattern of neutrophils emanating from a crypt, reminiscent of a volcanic eruption is pathognomonic for _____

C. difficile colitis

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