Introduction

• 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

Causes

• 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)

Presentation

• 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

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.

Pseudo-obstruction

• 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.