Large Bowel Obstruction
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Large bowel obstruction causes a less severe disease than small small bowel obstruction
  • Symptoms are more gradual in onset
  • There are often loud borborygmi (normal bowel sounds)
  • Rectum is usually empty, and the abdomen is non-tender
  • Pain is lower down in the abdomen
  • There may be greater distension than with small bowel obstruction
Large Bowel Obstruction
Large Bowel Obstruction. Note the dilated loops of large bowel.


  • Colon cancer
  • Benign strictures – e.g. diverticular disease, IBD, ischaemic bowel, radiation damage
  • Sigmoid volvulus
  • Intussusception
  • Herniae – not as common as in small bowel obstruction
  • Psuedo-obstruction (same as paralytic ileus, except it affects the large bowel)


  • Abdominal distension and absolute constipation
  • Vomiting – a very late sign
  • Patient may have history of history of change in bowel habit and / or rectal bleeding
  • Ask about family history – IBD and colon cancer

Closed loop obstruction

Ileo-caecal valve is competent and as a result fluids and other materials can continue to pass into the large intestine (the bowel produces up to 9L of fluid per day, so even if NBM, intestinal activity cannot be completely suppressed).  Colon distends massively (>12cm – normal <6cm), and the caecum is at risk of rupture and life-threatening faecal peritonitis.

Incompetent IC valve

  • The obstruction causes the small bowel to distend, and may induce vomiting
  • Not as urgent as closed loop obstruction, because perforation isn’t as bigger risk
  • Can be safely imaged with barium enema / endoscopy

Colonic stenting

  • Can be used in palliative care where surgery isn’t appropriate
  • Can also be used to buy time – ‘bridge to surgery’. The stent may allow the patient to recover enough to be fit enough for an operation.
  • Usually, it is colonic cancer that is stented.
  • Apple core stricture – a sign of colon cancer – is a sign on barium enema,where the lumen of the bowel looks a bit like an apple core due to the cancer causing a stricture.


  • Similar pathogenesis to paralytic ileus
  • You cant exclude mechanical obstruction without colonic imaging.
  • Mostly the same causes as paralytic ileus, but can be affected by drug use (e.g. anti-depressants), neurological disease and pneumonia.


  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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