Bowel obstruction

Question 1

Describe the pathophysiology of bowel obstruction

Answer 1

Obstruction of the bowel can cause congestion and dilatation of the bowel proximal, caused by a build up of food an secretions, which can disrupt peristalsis and propulsion of food

Question 2

How will upper small bowel obstruction usually present?

Answer 2

Acutely (Within hours) with large volumes of food being vomited back up

Question 3

How will distal small bowel or large bowel obstruction present?

Answer 3

Colicky abdominal pain and distension, with possibly faeculent vomit

Question 4

What are some mechanical causes of bowel obstruction?

Answer 4

Adhesions or bands
Incarcerated abdominal wall hernia
Internal hernia
Volvulus
Tumour
Inflammatory strictures
Bolus obstruction
Intussusception

Question 5

What are bands within the GI tract?

Answer 5

These are congenital bands of scar tissue which lie in the abdomen and can allow twisting of the bowel

Question 6

What are adhesions within the GI tract?

Answer 6

Adhesions are caused by previous surgery and cause mating together of bowels, which can twist

Question 7

How will a volvulus appear on X-ray?

Answer 7

Coffee bean appearance

Question 8

What are some common causes of inflammatory strictures?

Answer 8

Diverticular disease
Crohn’s disease

Question 9

What is a bolus?

Answer 9

A foreign body

Question 10

What are some examples of boluses that can obstruct the bowel?

Answer 10

Food bolus
Impacted faeces
Impacted gallstones ileus
Trichobezoar (Hair ball due to hair sucking)

Question 11

What is a trichobezoar?

Answer 11

A hair ball caused by sucking of the hair

Question 12

What is intussusception?

Answer 12

This is when a segment of the bowel wall becomes telescoped into the segment distal to it, usually initiated by a mass in the wall

Question 13

Who is most at risk of intussusception?

Answer 13

Children, due to more common enlargement of lymphatic tissue

Question 14

What occurs in bowel strangulation?

Answer 14

If the bowel becomes trapped and obstructed, there is an increase in internal pressure, which can increase pressure on veins, therefore decreasing venous return and thus arterial inflow, leading to infarction and perforation

Question 15

What is adynamic bowel obstruction?

Answer 15

This is bowel obstruction not with a mechanical cause that physically obstructs the bowel

Question 16

What are the 2 main types of adynamic bowel obstruction?

Answer 16

Paralytic ileus
Pseudo-obstruction

Question 17

What is paralytic ileus?

Answer 17

This is the disruption of the normal propulsive activity of the small bowel due to failure of peristalsis

Question 18

What are some risk factors of paralytic ileus?

Answer 18

Recent GI surgery
Inflammation due to peritonitis
Diabetic ketoacidosis

Question 19

What is Pseudo-obstruction also known as?

Answer 19

Ogilvie’s syndrome

Question 20

What is pseudo-obstruction (Ogilvie’s syndrome)?

Answer 20

This is the acute dilatation of the colon in the absence of colonic obstruction, in acutely unwell patients

Question 21

What are some risk factors of pseudo-obstruction?

Answer 21

Hip replacement
CABG
Spinal cord facture
Pneumonia
Elderly, frail patients

Question 22

What are some common symptoms in bowel obstruction?

Answer 22

Vomiting
Pain
Constipation
Distension
Complete or incomplete obstruction

Question 23

What does vomitus containing semi-digested food suggest in bowel obstruction?

Answer 23

A gastric outlet obstruction

Question 24

What does copious, bile stained vomitus suggest in bowel obstruction?

Answer 24

Upper small bowel obstruction

Question 25

What does faeculent vomitus suggest in bowel obstruction?

Answer 25

More distal obstruction

Question 26

What is meant by faeculent vomitus?

Answer 26

Thick, brown, foul-smelling vomitus

Question 27

How does pain occur in bowel obstruction?

Answer 27

Distension of the bowel can stimulate stretch receptors, while constriction of muscle around a blockage can also cause colicky pain

Question 28

What is meant by absolute constipation?

Answer 28

No passage of faeces or flatus rectally

Question 29

What can occur in the ileo-caecal valve remains competent in bowel obstruction (50% of cases)?

Answer 29

This prevents the backwards flow of bowel contents and gas into the small intestine, which causes is build up in the caecum, which has a thin wall and so can rupture

This is called a closed loop obstruction

Question 30

What can occur if ileo-caecal valve becomes incompetent in bowel obstruction?

Answer 30

The small bowel can become distended due to movement of bowel contents back in, therefore delaying symptom onset

Question 31

What can occur if there is chronic incomplete obstruction of the bowel?

Answer 31

This can cause gradual hypertrophy of the muscle, causing colicky pain during peristalsis of the hypertrophic muscle

Question 32

What are some physical signs of bowel obstruction?

Answer 32

Dehydration (Dry mouth, loss of skin turgor and elasticity)
Abdominal distension
Visible peristalsis
Relative lack of abdominal tenderness
Palpable mass on percussion
Central hyperresseonance due to gaseous distension
Tinkling bowel sounds

Question 33

What would obstruction with tenderness suggest?

Answer 33

Bowel strangulation

Question 34

What are some investigations performed in bowel obstruction?

Answer 34

Supine abdominal x-ray
CT scan

Question 35

What will be seen on supine AXR in bowel obstruction?

Answer 35

Distended loops of small bowel in the centre of the abdomen
Visible place circularis (valvulae conniventes)
Haustra coli span whole length of bowel

Question 36

What is the initial management technique for bowel obstruction?

Answer 36

Drip:
Nil by mouth
IV cannula
Bloods taken
IV fluids and electrolytes

Suck:
Nasogastric tube to suck out gasses