Intestinal Obstruction

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.

⭐ 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.

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. oka

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)
• 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.