Intestinal Obstruction

Question 1

What are the symptoms of intestinal obstruction?

Answer 1

Nausea/vomiting
-can be faeculent in low obstruction
Diffuse, central abdominal pain (colicky)
Constipation
Abdominal distension
Anorexia
Absolute constipation
-early in low obstruction
-late in high-level obstruction

Question 2

What are the signs of intestinal obstruction?

Answer 2

Signs of dehydration
Abdominal distension
Hyper-resonant bowel if distended
Bowel mass
Peritonism
Tinkling bowel signs

Question 3

What are the common causes of small bowel obstruction?

Answer 3

Adhesions

Hernias

Question 4

What are the common causes of large bowel obstruction?

Answer 4

Colon carcinoma
Constipation
Diverticular strictures
Vovlulus
-sigmoid
-caecal

Question 5

What are the rarer causes of bowel osbtruction?

Answer 5

Chron's stricture
Gallstone ileus
Intussusception
TB
Foreign body

Question 6

How can large and small bowel obstruction be distinguished clinically?

Answer 6

Small bowel
-vomiting occurs earlier
-less distension
-pain higher up
Large bowel
-pain is more constant

Question 7

What are the large and small bowel obstruction differences seen on an AXR?

Answer 7

Small bowel
-central gas shadows
-valvulae conniventes completely crossing lumen
-no gas in large bowel
Large bowel
-peripheral gas shadows proximal to blockage
-haustra not crossing whole lumen

Question 8

How can ileus and mechanical obstructions be distinguished?

Answer 8

Ileus - functional obstruction from reduced motility
No pain
Absent bowel sounds

Question 9

How can simple/closed loop/strangulated bowel obstructions be distinguished?

Answer 9

Simple - one obstructing point, no vascular compromise
Closed loop - obstruction at two points (risk of perforation)
Strangulated - compromised blood supply, sharper/localised pain, fever + WCC

Question 10

What are the complications of intestinal obstruction?

Answer 10

Fluid/electrolyte shifts
Vascular compromise
Sepsis

Question 11

What causes fluid shifts in bowel obstruction?

Answer 11

Internal loss (water pooling in bowel 1.5-3l)
External loss (vomiting, diarrhoea, fistulae)

Question 12

What causes the electrolyte shifts in bowel obstruction?

Answer 12

Loss of water causes electrolyte disturbances

• hyponatremia
• hypokalaemia
• metabolic alkalosis

Question 13

What causes vascular compromise in bowel obstruction?

Answer 13

Strangulation compromises blood supply

Leads to ischaemia –> necrosis of bowel

Question 14

What causes sepsis in bowel obstruction?

Answer 14

Perforation –> leaking of faecal matter into peritoneum

Severe infection, hard to clear

Question 15

What investigations are appropriate in a patient with suspected bowel obstruction?

Answer 15

AXR (supine + erect)
FBC, U&Es, Creatinine, Group + Cross match
Glucose
Water soluble contrast enema X-ray
CT 
MRI
USS (great at exclusion)