Large Bowel Obstruction

Question 1

What is the aetiology of LBO?

Answer 1

• Cancer
• Sigmoid volvulus
• Caecal volvulus
• Diverticular disease

Question 2

What are the symptoms and signs of LBO?

Answer 2

4 cardinal features;

• Vomitting
  
  • Faecalant vomitting (faecal is caused by fistula)
• Constant pain & tenderness
• Constipation (not always absolute)
• Distension

Question 3

What are the differential diagnoses of LBO?

Answer 3

• Constipation with impacted faeces
• Colonic pseudo-obstruction
  
  • Functional obstruction of colon leading to megacolon in the absence of obvious colonic diseases or mechanical obstruction
• Toxic dilatatation of colon

Question 4

What is the definition and differences between simple, closed lopp and strangulated obstructed bowel?

Answer 4

• Simple
  
  • 1 obstructing point & no vascular compromise
• Closed-loop
  
  • 2 obstruction points
  • forming loop of grossly distended bowel at risk of perforation
• Strangulated
  
  • Compromised blood supply
  • Sharper, more constant, localized pain than the central colic of obstruction
  • Peritonism is cardinal sign
  • Fever, inc. WBC and other signs of mesenteric ischaemia

Question 5

What is an ileus? And what is the difference between an ileus and mechanical obstruction?

Answer 5

Ilius is the loss of GI motility.

• Only refers to loss of peristalisis (not obstruction generally)

Differenes between ilius and obstruction;

• Ilius has no pain
• Ilius has absent bowel sound

Question 6

What investigations would you perform in suspected LBO?

Answer 6

Abdominal X-Ray

• Caecal distension
  
  • Peripher gas shadows proximal to blockage (caecum) [not rectum]
  • Caecum >10cm inc risk of rupture
  • Competent ileo-caecal valve inc risk of rupture (closed-loop obstruction)
• Haustra do not cross lumen width

Erect Chest X-Ray

• Suspected perforation

Contrast enema

• Essential to differentiate mechanical obstruction from pseudo-obstruction

FBC
U&E
CT

• Useful in malignant LBO as also identifies metastases

Question 7

Outline the general, non-operative and operative management of LBO?

Answer 7

General

• Drip & suck (IV fluids & NGT)
• Analgesia
• Oxygen
• Stop motility stimulants & ensure alternative routes for any medications

Non-operative management

• Sigmoid volvulus/ pseudo-obstruction
  
  • Riqid sigmoidoscopy & passage of flatus tube decompresses sigmoid volvulus
  • If fails attempt colonoscopic decompression
• Malignant LBO
  
  • Self-expanding metal stents (temp. or permanently)

Operative management

• Most appropriate procedure
  
  • Bowel resection and/or colostomy/ ileostomy/ caecostomy