Bowel Obstruction

Question 1

What is meant by bowel obstruction?

Answer 1

• Dilatation of bowel proximal

- Peristalsis is disrupted

Question 2

How does a patient present with an upper small bowel obstruction?

Answer 2

• Acute presentation (within hours)

- Large volumes vomited

Question 3

What symptoms would indicate a distal small bowel or a large bowel obstruction?

Answer 3

• Colicky abdominal pain and distension.
• Vomiting (possibly ‘faeculent’)
• Constipation
• Complete/ Incomplete obstruction

Question 4

Vomiting can still occur even if a patient takes nothing by mouth. TRUE/FALSE?

Answer 4

TRUE
Due to GI secretions still being produced
- Saliva
- gastric secretions
- pancreatic secretions
- bile

Question 5

HOw can the consistency of vomit give a clue as to where a GI obstruction is?

Answer 5

• Semi-digested food (no bile) = gastric outlet obstruction
• Bile-stained fluid suggests = small bowel obstruction
• Thicker, brown, foul-smelling vomitus (‘faeculent’) = distal obstruction

Question 6

Why does bowel obstruction cause absolute constipation?

Answer 6

Bowel gas is absorbed distal to the obstruction.
=> neither faeces or flatus passed rectally

=> pathognomonic of bowel obstruction.

Question 7

HOw can an incompetent ileo-caecal valve delay the onset of symptoms?

Answer 7

Allows blockage to reflux back into small bowel

=> gives it more room to block

Question 8

What are the physical signs of intestinal obstruction?

Answer 8

• Dehydration (dry mouth, loss of skin elasticity)
• Abdominal distension
• Visible peristalsis

Question 9

What is the most useful initial investigation if you suspect a patient has a bowel obstruction?

Answer 9

supine abdominal X-ray:

Question 10

Describe how dilated small bowel loops appear on an abdominal X-Ray

Answer 10

• Distended small bowel loops
• lie in a central position
• valvulae coniventes (all way across bowel diameter)

Question 11

Describe how distended large bowel appears on an abdominal X-Ray

Answer 11

• lie in its anatomical position

- haustra coli (dont extend all way across bowel)

Question 12

What is involved in the initial management of intestinal obstruction?

Answer 12

• Nil by mouth.
• Insert IV cannula and send blood
• Resuscitate with IV fluids, replacing electrolyte losses.
• NG tube to decompress the stomach.

Question 13

What are the potential mechanical causes of intestinal obstruction?

Answer 13

• Adhesions
• Abdominal wall hernia
• Volvulus
• Tumour
• Inflammatory strictures
• Bolus obstruction
• Intussusception

Question 14

HOw do patient’s acquire adhesions in the bowel?

Answer 14

• congenital
• from previous abdominal surgery
• from peritonitis

Question 15

What is an inguinal hernia?

Answer 15

Dilated loop of bowel escapes through a defective inguinal ring

Question 16

What inflammatory conditions can cause bowel strictures that may result in obstruction?

Answer 16

• IBD (UC/Crohn’s)

Question 17

What can cause a bolus obstruction?

Answer 17

Food bolus
Impacted faeces
Impacted ‘gallstone ileus’ (rare)
Trichobezoar (rare)

Question 18

What happens in intussusception?

Answer 18

a segment of bowel wall becomes telescoped into the segment distal to it.

Common in children.

Question 19

What usually causes intussusception to occur?

Answer 19

• initiated by a mass in the bowel wall

=> e.g. enlargement of lymphatic tissue or tumour

Question 20

Intussusception is most common in which group of patients?

Answer 20

Children

Question 21

What symptom can be an indication of bowel strangulation?

Answer 21

Pain over a hernia

Question 22

What are the potential causes of an adynamic bowel obstruction?

Answer 22

• Paralytic ileus (i.e. bowel cant perform peristalsis)

- Pseudo-obstruction

Question 23

What are the risk factors for a paralytic ileus?

Answer 23

• Recent GI surgery
• Inflammation with peritonitis
• Diabetic keto acidosis

Question 24

How is a paralytic ileus treated?

Answer 24

‘drip and suck’ while awaiting restoration of peristalsis

- i.e. fluids and an NG tube

Question 25

What is a pseudo-obstruction?

Answer 25

- Acute dilatation of the colon | - absence of obstruction in acutely unwell patients

Question 26

What is linked to pseudo obstruction?

Answer 26

``` Hip replacement surgery Coronary Artery Bypass Grafts Spinal # Pneumonia Frail / elderly patients ```

Question 27

How is pseudo obstruction confirmed?

Answer 27

AXR +/- CT | - shows gaseous distension to distal rectum