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Bowel obstruction

Classification of Intestinal Obstruction

Mechanical

  • Obstruction
    • Foreign body
    • Tumour inside intestinal wall
    • Tumour outside intestinal wall
  • Strangulation
    • Vovulus
    • Nodulus
    • Intussusception
  • Adhesion

Adynamic

  • Spastic
  • Paralytic

Etiology

  • Gallstones can lead to biliary ileus
    • If gallstone is >2cm it can lead to aseptic inflammation → leads to adhesion between gallbladder and small intestine → decubitus of wall occurs (cholecysto-enteric fistula) → gallstone is able to pass directly through intestine and most commonly causes obstruction at distal ileum
    • Rigler’s triad – pneumobilia, small bowel obstruction, radio-opaque gallstone
  • Foreign body, bezoars
  • Tumours, Crohn’s disease, strictures

Pathophysiology and Clinical features

Obstruction – colicky pain

  • Initially there is an increase in peristalsis in an effort to propel contents of the lumen past the obstruction
  • In relation to the obstruction
    • Proximal portion of the intestine is dilated – necrosis occurs >24 hours as ↑intra-luminal pressure compresses vessels
    • Distal portion is small and lacks contents – necrosis occurs within 24 hours

Strangulation – non-colicky, constantly increasing pain

  • There is simultaneous obstruction and cessation of blood supply
  • Necrosis occurs within 6-12 hours
  • Peritonitis and shock >24 hours

General features

  • Nausea and vomiting – initially the contents are stomach, then duodenal and bile, and then intestinal
  • Abdominal distension
  • Absent bowel sounds
  • Stage of decompensation – necrosis of nerves of visceral and parietal peritoneum

Stages

  • 1st stage – pain located at site of blockage
  • 2nd stage – diffuse pain, sign of peritonitis
  • 3rd stage – no pain on palpation

Investigations

  • Determine etiology of obstruction
  • Distinguish partial from complete obstruction
  • Distinguish simple from strangulated obstruction
  • XR – dilated small bowel; foreign body may be seen
  • Contrast radiograph with gastrograffin – to show degree of obstruction

Treatment

  • Fluid and electrolyte
  • Monitor vitals and urine output
  • NGT to decrease vomiting and risk of aspiration
  • Analgesia can mask signs of peritoneal irritation
  • Complete obstruction – surgery
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