Small bowel obstruction

Question 1

What are the consequences of small bowel obstruction?

Answer 1

Dilatation of bowel proximal

Peristalsis is disrupted

Question 2

What is absolute constipation?

Answer 2

Patient is not passing faeces or gas

Question 3

What is the presentation of a distal small bowel/large bowel obstruction?

Answer 3

Colicky abdominal pain and distension

Vomiting - faeculent

Question 4

What type of vomiting suggests gastric outlet obstruction?

Answer 4

Semi-digested food eaten a day or two previously (no bile)

Question 5

What is classic of an upper small bowel obstruction?

Answer 5

Acute presentation

Large volumes vomited - Copious bile-stained fluid

Question 6

What are the symptoms of intestinal obstruction?

Answer 6

Distension of the bowel causes pain

Intermittent episodes of colicky pain

Question 7

What is closed loop obstruction?

Answer 7

The thin walled caecum progressively distends with swallowed air and eventually may rupture

Question 8

What happens in large bowel obstruction if the ileocaceal valve remains competent?

Answer 8

backward flow of accumulated bowel contents is prevented

Question 9

What happens in large bowel obstruction if the ileocaceal valve becomes incompetent?

Answer 9

the small bowel distends, delaying the onset of symptoms

Question 10

What may happen in incomplete obstruction?

Answer 10

vomiting may be intermittent and bowel habit erratic

Question 11

What does chronic icomplete obstruction lead to?

Answer 11

gradual hypertrophy of the muscle of the bowel wall proximally.

Peristaltic activity in this hypertrophic muscle is responsible for bouts of colicky pain which can be more prominent than in complete obstruction.

Question 12

What are some physical signs of intestinal obstruction?

Answer 12

On percussion the centre of the abdomen tends to be resonant due to gaseous distension
Dehydration (dry mouth, loss of skin turgor and elasticity)
Relative lack of abdominal tenderness (obstruction with tenderness may indicate bowel strangulation)
Bowel sounds high-pitched and tinkling

Question 13

What does fluid in the abdomen sound like on auscultation?

Answer 13

echoing

Question 14

What is the first line investigation for bowel obstruction?

Answer 14

abdominal xray

Question 15

What investigation is performed to comfirm the diagnosis?

Answer 15

CT scan

- transition point on CT scan with distended bowel proximal and collapsed bowel distal to the site of obstruction

Question 16

What is the inital management of small bowel obstruction?

Answer 16

Drip and suck (IV fluids and NG tube)

Question 17

What are the mechanical causes of small bowel obstruction?

Answer 17

Adhesions or bands
Incarcerated abdominal wall hernia
Internal hernia
Volvulus
Tumour
Inflammatory strictures - crohns and diverticular 
Bolus obstruction
Intussusception

Question 18

What are the two causes of adynamic bowel obstruction?

Answer 18

Paralytic ileus

Pseudo-obstruction

Question 19

What is a paralytic ileus?

Answer 19

Disruption of the normal propulsive activity of the GI tract, due to failure of peristalsis
- normally occurs after surgery

Question 20

Describe Pseudo-obstruction?

Answer 20

AXR +/- CT confirms gaseous distension to distal rectum

Colon may require colonoscopic decompression if distension is causing pain or respiratory compromise