Presentation, diagnosis and management of bowel obstruction

Question 1

Describe roughly the pathophysiology of upper small bowel obstruction?

Answer 1

Acute presentation
Hours of onset
Large volumes vomited

Question 2

Describe roughly the pathophysiology of distal small bowel/large bowel obstruction?

Answer 2

Colicky abdominal pain and distention

Vomiting (possibly faeculent)

Question 3

When might vomiting develop earlier in obstruction?

Answer 3

The more proximal the obstruction is

Question 4

Describe what semi-digested food eaten a day or two perviously (no bile) being vomited would suggest?

Answer 4

Suggests gastric outlet obstruction

Question 5

Describe what copious bile -stained fluid being vomited suggests?

Answer 5

Upper small bowel obstruction

Question 6

Describe what thicker brown, foul-smelling vomitus suggests?

Answer 6

A more distal obstruction

Question 7

What is absolute constipation and what is it a major sign of?

Answer 7

It is neither faeces or flatus passed rectally

It is a sign of bowel obstruction

Question 8

Describe how symptoms tend to develop in the large bowel obstruction?

Answer 8

More gradually due to the capacity of the colon and caecum and their absorptive activity

Question 9

What might happen to the caecum in large bowel obstruction?

Answer 9

Due to its thin was the caecum might distend with swallowed air and eventually rupture - closed loop obstruction

Question 10

What happens in large bowel obstruction if the ileo-caecal valve becomes incompetent?

Answer 10

The small bowel distends, delayed the onset of the symptoms

Question 11

Describe what might happen in chronic incomplete obstruction?

Answer 11

Can lead to 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 might be some physical signs of intestinal obstruction?

Answer 12

Dehydration - dry mouth, loss of skin turgor and elasticity
Abdominal distention
Visible peristalsis
Relative lack of abdo tenderness

Question 13

What can a bowel obstruction presenting with abdo tenderness indicate?

Answer 13

Bowel strangulation

Question 14

What is the most useful investigation for suspected bowel obstruction?

Answer 14

Supine abdo Xray

• bowe proximal to the obstruction is distended with gas

Question 15

What investigation might be done after the Xray to confirm diagnose and look for a cause?

Answer 15

CT scan

Question 16

What is the initial management of intestinal obstruction?

Answer 16

Nil by mouth
IV cannula and send blood
Resuscitate with IV fluids, replacing electrolyte losses
Pass a NG tube to decompress stomach

Question 17

How might adhesions or bands cause bowel obstruction?

Answer 17

Congenital or resulting from previous abdo surgery or peritonitis

Question 18

What is a volvulus?

Answer 18

A mobile loop of bowel rotates causing obstruction at its neck - causing obstruction

Question 19

Describe inflammatory strictures as a cause of bowel obstruction?

Answer 19

Crohns disease (inflammation, stricture, fistula...)
Diverticular disease 

• obstructions usually incomplete

Question 20

What is intussusception?

Answer 20

A segment of bowel wall becomes telescoped into the segment distal to it

Usually initiated by a mass in the bowel wall

Common in kids

Question 21

What is bowel strangulation?

Answer 21

A segment of bowel becomes trapped - lumen becomes obstructed

Venous return is obstructed

Rising local intravascular pressure - arterial inflow is compromised

IF strangulation is not relieved this will progress to infarction and perforation

Question 22

When might bowel strangulation occur?

Answer 22

In external hernia or volvulus

Question 23

What might pain over a hernia indicate?

Answer 23

Possible strangulation - and its a sign of requiring urgent surgical intervention

Question 24

What is paralytic ileus?

Answer 24

Disruption of the normal propulsive activity of the GI tract- due to failure of peristalsis

Question 25

What are some risk factors for paralytic ileus?

Answer 25

Recent GI surgery
Inflammation with peritonitis
Diabetic keto acidosis

Question 26

What is the treatment of paralytic ileus?

Answer 26

Drip and suck - while awaiting restoration of peristalsis

Question 27

Describe pseudo-obstruction (Ogilvie’s syndrome) in terms of adynmaic bowel obstruction?

Answer 27

Acute dilatation of the colon in the absence of colonic obstruction in acutely unwell patients