Small bowel obstruction

In small bowel obstruction, the passage of food, fluids and gas, through the small intestines becomes blocked.

Adhesions (e.g. following previous surgery) are the most common cause of small bowel obstruction, followed by hernias.

Features

• diffuse, central abdominal pain
• nausea and vomiting
  • typically bilious vomiting
• 'constipation' with complete obstruction and lack of flatulence
• abdominal distension may be apparent, particularly with lower levels of obstruction
• 'tinkling' bowel sounds (more common in early bowel obstruction)

Diagnosis

• CT
  • definitive investigation and is more sensitive, particularly in early obstruction
  • should be done first-line - the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) reports getting an abdominal x-ray first can delay treatment and may contribute to patient harm due to delayed definitive management
• abdominal x-ray
• distended small bowel loops with fluid levels
  • considered dilated if small bowel is >3cm diameter

Management

• intial steps:
  • NBM
  • IV fluids
  • antiemetics: e.g. cyclizine – useful for general nausea; caution if bowel distension is severe due to anticholinergic effects
  • nasogastric tube with free drainage
• some patients settle with conservative management but otherwise will require surgery