Intestinal Obstruction

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Obstruction 101 - Know Thy Enemy

  • Definition: Cessation or impairment of normal aboral passage of intestinal contents.
  • Mechanical Types:
    • Simple: Lumen blocked; vascularity intact.
    • Strangulated: Blood supply compromised → ischemia, gangrene, perforation.
  • Functional Type: Adynamic/Paralytic Ileus (impaired peristalsis).
  • Classifications:
    • Small Bowel (SBO) vs. Large Bowel (LBO).
    • Acute vs. Chronic; Partial vs. Complete. Radiograph of intestinal obstruction

⭐ Strangulation implies vascular compromise, a surgical emergency often presenting with persistent pain, tenderness, and systemic toxicity if delayed treatment occurs.

Etiology - The Usual Suspects

  • Small Bowel Obstruction (SBO):
    • Adhesions (most common, esp. post-operative)
    • Hernias (external e.g., inguinal, femoral; or internal)
    • Malignancy (primary small bowel tumors or metastases)
    • Inflammatory (Crohn's disease strictures)
    • 📌 Mnemonic (SBO): "ABC" - Adhesions, Bulges (Hernias), Cancer/Crohn's.
  • Large Bowel Obstruction (LBO):
    • Malignancy (colorectal cancer - leading cause)
    • Volvulus (sigmoid most common, then cecal)
    • Diverticular disease (strictures, inflammation)
    • Fecal impaction (elderly, constipated)
  • Less Common / Specific Populations:
    • Intussusception (commonest cause in children <2 yrs)
    • Gallstone ileus (elderly females)

⭐ Post-operative adhesions account for ~75% of all small bowel obstructions.

Causes of Bowel Obstructions

Clinical Picture - Gut's Distress Call

  • Cardinal features (📌 PAVO):
    • Pain: Colicky, severe; becomes constant if strangulation.
    • Abdominal distension: More pronounced in LBO.
    • Vomiting: Early, profuse in SBO; late, feculent in LBO.
    • Obstipation: Absolute constipation (no flatus/feces).
  • Examination findings:
    • Visible peristalsis (early, especially in thin patients).
    • High-pitched "tinkling" bowel sounds (early); absent (late/ileus).
    • Tenderness, guarding, rigidity (suggest peritonism/strangulation).
    • Dehydration signs (tachycardia, dry tongue, ↓ urine output).

⭐ Strangulation features: Fever, persistent tachycardia (>100/min), localized tenderness/peritonism, leukocytosis, shock. Early diagnosis is key to reduce mortality. Abdominal distension in intestinal obstructionoka

Diagnostic Clues - Spotting the Block

  • Initial Imaging:
    • X-Ray Abdomen (Supine & Erect):
      • Dilated loops: SBO >2.5 cm, LBO >6 cm, Cecum >9 cm (📌 Rule of 3-6-9)
      • Multiple air-fluid levels (>2.5 cm wide, stepladder)
      • Gasless abdomen (strangulation risk) X-ray showing air-fluid levels in intestinal obstruction
  • Gold Standard:
    • CT Scan (Abdomen & Pelvis with contrast):
      • Identifies transition point, cause, severity.
      • Detects ischemia (wall thickening, pneumatosis, portal venous gas).
  • Contrast Studies:
    • Gastrografin (SBO): diagnostic & therapeutic.
    • Contrast Enema (LBO): locates obstruction.
  • Labs: CBC, electrolytes, lactate (↑ in ischemia).

⭐ CT scan is the investigation of choice for confirming intestinal obstruction, pinpointing the site, etiology, and detecting complications like ischemia.

Management - Clearing the Way

  • Initial: NPO, IV fluids, NG tube, catheter. Analgesia.
  • Antibiotics if strangulation suspected.
  • Conservative (uncomplicated SBO): Monitor. Failure if no improvement in 24-48 hrs or worsening.
  • Surgical: For strangulation, perforation, complete obstruction, failed conservative. Goal: relieve obstruction.

⭐ In suspected strangulated SBO, early surgery is vital to prevent bowel necrosis & ↓ mortality.

High‑Yield Points - ⚡ Biggest Takeaways

  • Adhesions: Most common cause of Small Bowel Obstruction (SBO).
  • Malignancy: Most common cause of Large Bowel Obstruction (LBO).
  • Cardinal symptoms: Colicky pain, vomiting, abdominal distension, absolute constipation.
  • SBO on X-ray: Central dilated loops (>3cm), multiple air-fluid levels, valvulae conniventes.
  • LBO on X-ray: Peripheral dilated colon (>6cm), haustra.
  • Strangulation (fever, tachycardia, peritonism) requires urgent surgical intervention.
  • Initial management: NPO, IV fluids, NG tube decompression.

Practice Questions: Intestinal Obstruction

Test your understanding with these related questions

Assertion: Crohn's disease only affects the colon. Reason: Crohn's disease typically involves full-thickness inflammation of the bowel wall.

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Flashcards: Intestinal Obstruction

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The most common site of gastrointestinal ischemia is the _____

TAP TO REVEAL ANSWER

The most common site of gastrointestinal ischemia is the _____

colon

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