ISSN 2398-2950      

Intestine: obstruction

ffelis
Contributor(s):

Ed Hall

Cheryl Hedlund

Synonym(s): Intestinal blockage Intestinal foreign bodies


Introduction

  • Bowel obstruction is a frequent occurrence and is the most common indication for surgical intervention involving the gastrointestinal tract.
  • Classified as simple (mechanical or functional), or strangulated   Intestine: strangulated obstruction / hernia  .
  • Simple obstructions can be high (proximal), and involve the pylorus, duodenum and the proximal jejunum. A low (distal), small bowel obstruction involves the lower one-half of the jejunum and ileum.
  • Cause:
  • Signs: variable but may include dehydration, hypovolemic shock   Shock  , endotoxic shock   Shock: septic  , and death.
  • Diagnosis: radiography.
  • Treatment: usually surgical intervention.
  • Prognosis: higher mortality rates are associated with strangulation and high obstructions.

Pathogenesis

Etiology

Pathophysiology

  • Distension of the bowel begins proximal to the obstruction, thus causing fluid and gas accumulation.
  • The content of the fluid will depend upon the location of the obstruction.
  • Large foreign body   →   ulceration and pressure necrosis.

Proximal obstruction

  • High intramural pressure   →   compromized blood supply   →   possible shunting away from intestinal capillaries to arteriovenous anastomoses   →   hypoxia to the bowel, loss of viability and increased permeability to toxins, including endotoxins.
  • Duodenum is more sensitive to circulatory changes associated with distension.

Obstruction proximal to the pylorus

  • Hydrogen ion loss    →   metabolic alkalosis often with hypokalemia.

Obstruction below the pancreatic and biliary ducts

  • Vomiting and loss of absorption of fluid collecting proximal to the obstruction   →   rapid and severe losses with significant amount of bicarbonate ion   →   dehydration and/or hypovolemic shock   →   metabolic acidosis due to lactic acidosis.

Distal obstruction

  • Fluid and electrolyte losses less severe but significant in chronic cases.
  • Less severe distension of intestinal wall   →   circulation of affected intestine unimpeded.

Strangulation

  • Partial or total obstruction of venous drainage and an intact arterial supply   →   intramural sequestration of blood and eventually bowel wall edema.
  • Distended bowel proximal to the strangulation filled with gas and fluid containing a significant amount of blood   →   non-viable and necrotic bowel wall   →   transmural migration of toxins and bacteria   →   hypovolemia, endotoxic shock and death.

Timecourse

  • Acute: proximal and strangulated obstruction.
  • Chronic: low obstruction.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Barrs V R, Beatty J A, Tisdall P L et al (1999) Intestinal obstruction by trichobezoars in five cats. J Fel Med Surg (4), 199-207 PubMed.

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