Clinical Features

The cardinal signs of mechanical bowel obstruction are abdominal pain, vomiting, constipation, abdominal distention, and decreased bowel sounds, regardless of the underlying etiology. The severity and progression of clinical features differ according to the site and severity of the obstruction.

• Complete bowel obstruction

  • Total obstruction of the intestinal lumen, preventing the passage of air and fluid

  • Rapid progression of clinical features

  • Can be associated with obstipation (complete inability to pass stool or gas)

• Partial bowel obstruction

  • Partial obstruction of the intestinal lumen, allowing a small amount of air and fluid to pass through

  • Clinical features may be less severe than in complete bowel obstruction

  • Can be associated with the intermittent passage of flatus and overflow diarrhea

Partial bowel obstruction causes gradually progressive symptoms that are typically milder than those caused by complete obstruction. Obstipation is only present in complete bowel obstruction.

Depending on the onset and progression of clinical features, mechanical bowel obstruction can be classified as simple or complicated and acute or subacute.

• Simple bowel obstruction: bowel obstruction with no evidence of complications (i.e., no features of bowel ischemia, bowel perforation, or red flags for complicated bowel obstruction)

  
  

  Complicated bowel obstruction: bowel obstruction associated with strangulation, ischemic necrosis, or perforation

• Red flags for complicated bowel obstruction

  • Pain out of proportion

  • Peritoneal signs

  • Signs of systemic toxicity, e.g., SIRS

  • Hemodynamic instability

  • Laboratory abnormalities: e.g., significant leukocytosis, metabolic acidosis, ↑ lactate