Intestinal Obstruction (Surgical Approach)

Clinical assessment

History (pain characteristics, vomiting, bowel function changes, previous surgery). Examination (distension, bowel sounds - high pitched early -> absent late, tenderness, hernia checks, rectal exam). Assess hydration/shock status.

Differential diagnosis

• Paralytic Ileus (post-op, sepsis, electrolyte imbalance - usually diffuse dilation, minimal pain).
• Pseudo-obstruction (Ogilvie's syndrome).
• Acute appendicitis.
• Acute pancreatitis.
• Peritonitis.
• Acute mesenteric ischaemia.

Investigations

• Abdominal X-ray (Supine and Erect/Left Lateral Decubitus): Look for dilated bowel loops (>3cm small bowel, >6cm colon, >9cm caecum), multiple air-fluid levels (differing heights), paucity of gas distally.
• CT Scan Abdomen/Pelvis (with contrast): More sensitive and specific, identifies level and often cause of obstruction, detects complications (strangulation, perforation).
• Blood tests: FBC, Urea/Electrolytes/Creatinine (assess dehydration, electrolytes), Lactate (ischaemia).

Diagnostic criteria

Clinical suspicion supported by characteristic X-ray or CT findings.

Non-pharmacological management

• Pre-operative Resuscitation (CRITICAL):
• - IV Fluids: Aggressive resuscitation with isotonic crystalloids (Normal Saline, Ringer's Lactate) to correct dehydration and ongoing losses. Monitor haemodynamics & urine output (aim >0.5-1.0 ml/kg/hr). May take hours.
• - Nasogastric (NG) Tube Decompression: Insert NGT on free drainage/low suction to empty stomach/proximal bowel, reduce vomiting/aspiration risk.
• - Nil Per Os (NPO).
• - Urinary Catheter: Monitor urine output accurately.
• Intra-operative:
• - Replace blood loss, aspirated fluid, third-space losses.
• - Maintenance fluids (e.g., 5ml/kg/hr).
• Post-operative:
• - Continue IV fluids initially (e.g., NS/RL:Dextrose 1:2), monitor fluid balance, electrolytes.
• - Gradual reintroduction of oral intake as bowel function returns (flatus, bowel sounds, reduced NG output).
• - NG tube removal when appropriate.
• Non-operative Management (Selective Cases ONLY - e.g., adhesions, pseudo-obstruction, specific inflammatory conditions):
• - Requires close monitoring (pain, distension, NG output, vitals).
• - NGT decompression, IV fluids, +/- antibiotics.
• - Consider surgery if no improvement within 48-72 hours or signs of strangulation/perforation develop.

Pharmacological treatment

• Pre-operative:
• - Antibiotics: Broad-spectrum IV antibiotics covering Gram-negatives and anaerobes (e.g., Ceftriaxone 2g IV OD + Metronidazole 500mg IV Q8H).
• - Analgesia: Opioids (e.g., Pethidine 50-100mg IV/IM or Morphine) for severe colicky pain.
• Post-operative:
• - Continue analgesia (various options - opioids, NSAIDs, paracetamol).
• - Continue antibiotics if indicated (peritonitis, bowel resection).

Surgical Management

• Laparotomy: Explore abdomen to identify the cause and site of obstruction.
• - Relief of Obstruction: Divide adhesions (adhesiolysis), Reduce hernia, Resect tumour, Untwist volvulus, Decompress bowel.
• - Assess Bowel Viability: Check colour, peristalsis, arterial pulsations. Resect non-viable bowel with anastomosis or stoma formation.
• - Decompression: Milking bowel contents proximally or intraoperative decompression.
• - Lavage: If contamination/peritonitis present.

Monitoring

Pre-op: Vital signs, urine output, abdominal exam, NG output. Post-op: Vital signs, fluid balance, wound check, return of bowel function (flatus, bowel sounds, bowel movements), NG output.