Large Bowel Obstruction

Question 1

Definition of large bowel obstruction

Answer 1

Mechanical disruption to flow of contents in large bowel

Question 2

Aetiology of large bowel obstruction

Answer 2

Has many causes:
◦ Colorectal carcinoma (most common)
◦ Diverticular disease
◦ Volvulus
◦ Faecal impaction

• Can be simple or strangulating (blood supply cut off)

Question 3

History and examination of large bowel obstruction

Answer 3

• Colicky abdominal pain: cramping, severe and intermittent (continuous can indicate ischaemia)
• Abdominal distention
• Constipation/failure to pass flatus: absolute constipation is an earlier sign in large bowel obstruction
• Hard faeces: hard faeces on DRE May indicate faecal impaction
• Weight loss: can indicate malignancy
• Nausea and vomiting: later sign in large bowel obstruction, can be faecal vomiting (late sign)
• Peritonism: may indicate bowel perforation

Question 4

Investigations for large bowel obstruction

Answer 4

• Erect abdominal X ray: dilated large bowel peripherally. The haustrations of the taenia coli visible, but may not extend across whole width of bowel
• Urgent CT abdo pelvis: is able to diagnose and determine the cause of obstruction
• FBC: check for ischaemia/perforation
• ABG: to check for lactate to check for ischaemia

Question 5

Treatment of large bowel obstruction

Answer 5

GENERAL:
1) Supportive care:
◦ FLUID RESUSCITATION and NG TUBE DECOMPRESSION
◦ Consider analgesia
◦ NBM

CONSERVATIVE:
• Stool evacuation for stool impaction
• Rigid sigmoidoscopy decompression for sigmoid volvulus

SURGERY (peritonitis, or suspect ischaemia/perforation):
1) Emergency surgery: exploratory laparotomy/laparoscopy. May need stoma formation

Question 6

Complications and prognosis of large bowel obstruction

Answer 6

• Intestinal necrosis
• Sepsis
• Multi-organ failure
• Intestinal perforation

Timely treatment allows for good prognosis. Surgery can increase the risk of later obstruction due to more adhesions