Bowel Obstruction

Question 1

What is the normal size of the large bowel?

Answer 1

6cm diameter.

Question 2

What is the normal size of the small bowel?

Answer 2

2.5cm diameter.

Question 3

What is the size of the large bowel when distended?

Answer 3

> 12cm diameter.

Question 4

What is the size of the small bowel when distended?

Answer 4

> 5cm diameter.

Question 5

What are the causes of large bowel obstruction?

Answer 5

Colon cancer.
Benign strictures such as IBD, diverticular disease, ischaemia.
Sigmoid volvulus.
If in children suspect intersusseption as a cause.

Question 6

What are the causes of small bowel obstruction?

Answer 6

Adhesions from previous surgeries.
Strangulated hernias.
Tumours.
Volvulus.
If in children suspect intersusseption as a cause.

Question 7

What are the signs and symptoms of large bowel obstruction?

Answer 7

Abdo distension.
Loud normal bowel sounds.
Abdomen non-tender. 
Rectum empty.
Absolute constipation.
Vomiting (late stage).

Question 8

What are the signs and symptoms of small bowel obstruction?

Answer 8

Abdo distension.
High pitched tinkling bowel sounds.
Dilated loops of bowel may be palpable. 
Colicky umbilical abdo pain.
Vomiting which provides pain relief.

Question 9

How would a large bowel obstruction present on abdominal x-ray?

Answer 9

Dilations >6cm (9cm at caecum) in a peripheral location with haustra lines crossing edges of bowel.

Question 10

How would a small bowel obstruction present on abdominal x-ray?

Answer 10

Dilations >3cm in a central location with valvulae conniventes crossing the entire bowel.

Question 11

What investigations should be performed if bowel obstruction is suspected?

Answer 11

ABG to check lactate for signs of ischaemic bowel.
AXR.
CT scan to more accurately locate cause and differentiate between obstruction and pseudo-obstruction (inability of the small bowel to adequately peristalse).

Question 12

How is a large bowel obstruction managed?

Answer 12

Fluid resus and intestinal decompression.
Analgesia.
Stenting endoscopy.
If sigmoid volvulus do sigmoidoscopy.

Question 13

How is a small bowel obstruction managed?

Answer 13

Fluid resus and tube for decompression.
May need laparotomy.
If due to adhesions - ‘drip and suck’.

Question 14

What are the possible complications of bowel obstruction?

Answer 14

Ischaemic bowel.
Perforation leading to peritonitis.
Dehydration.
Renal impairment.