Large bowel obstruction

Question 1

What are 4 possible features of the presentation of large bowel obstruction?

Answer 1

1. Abdominal pain - often cramping
2. Bloating
3. Absolute constipation - not passing wind or faeces
4. Nausea and vomiting - but more common in small. Later sign in large

Question 2

What are 5 causes of large bowel obstruction?

Answer 2

1. Colonic tumour
2. Strictures - secondary to diverticular disease, or other conditions such as inflammatory bowel disease or post-surgical anastomosis
3. Volvulus - sigmoid or caecal
4. Hernias
5. Adhesions

Question 3

What is the commonest cause of large bowel obstruction?

Answer 3

colonic tumour

Question 4

What are 3 things which may cause strictures leading to large bowel obstruction?

Answer 4

1. secondary to diverticular disease
2. other conditions such as inflammatory bowel disease
3. post-surgical anastomosis

Question 5

What are 2 key investigations to perform in suspected large bowel obstruction?

Answer 5

1. Abdominal x-ray - to confirm diagnosis
2. CT abdomen - to establish cause
3. Barium or water-soluble contrast enema

Question 6

What is the role of abdominal x-ray in large bowel obstruction?

Answer 6

helps to establish diagnosis of large bowel obstruction

Question 7

What are 4 benefits of performing CT abdomen in large bowel obstruction?

Answer 7

1. establish cause e.g. malignancy
2. provide information such as transition point
3. distinguishing between caecal and sigmoid volvulus
4. signs of bowel ischaemia

Question 8

What is the nature of vomiting in large bowel obstruction?

Answer 8

more likely to be a late sign than in small bowel obstruction; initially bilious, may become faeculent as progresses

Question 9

Where are dilated bowel loops likely to be in large bowel obstruction?

Answer 9

predominantly peripheral

Question 10

What is the 3-6-9 rule of bowel dilatation on imaging?

Answer 10

1. small bowel dilatation if >3cm
2. large bowel dilatation if >6cm
3. caecal dilatation if >9cm

Question 11

What are 3 signs of bowel ischaemia on CT-AP in bowel obstruction?

Answer 11

1. unenhanced bowel loops
2. pneumatosis intestinalis (intramural bowel gas - within wall of bowel)
3. mesenteric fat stranding

Question 12

What is meant by the transition point, shown on CT in bowel obstruction?

Answer 12

sudden narrowing of bowel lumen at the site of obstruction

Question 13

What are 3 indications to performing abdominal ultrasound as an imaging modality in bowel obstruction?

Answer 13

1. perform in children/pregnancy - reduce radiation exposure
2. critically ill patients - easy bedside test
3. contrast allergy

Question 14

What are 3 types of CT-AP that can be performed in bowel obstruction and what is the indication for each?

Answer 14

1. IV and oral contrast: best initial test in haemodynamically stable patients with suspected partial bowel obstruction
2. IV contrast: indicated in suspected complete bowel obstruction
3. Non-contrast: indicated in patients with contrast allergy and suspected complete bowel obstruction

Question 15

Wen is a barium or water-soluble contrast enema performed?

Answer 15

in suspected distal LBO

Question 16

What are 3 things which may be seen with a barium or water-soluble contrast enema on AXR?

Answer 16

1. Tapering of bowel lumen at site of obstruction; no contrast visible beyond if complete obstruction, trickle beyond if partial
2. Bird beak sign: volvulus
3. Apple core sign: colonic malignancy

Question 17

When is the apple core sign seen on a barium/contrast enema on AXR?

Answer 17

colonic malignancy

Question 18

When is the bird beak sign seen on AXR with barium/ water soluble contrast enema?

Answer 18

volvulus

Question 19

What should you use when imaging with contrast and perforation is expected?

Answer 19

use a water-soluble oral contrast

Question 20

What are 4 aspects of the management of large bowel obstruction?

Answer 20

1. Supportive care - analgesia, IV fluids, anti-emetics, drip+suck
2. Decompression of sigmoid volvulus with flexi sig
3. Surgical intervention - laparoscopic or open colonic resection
4. Palliative care in some patients with malignant large bowel obstruction

Question 21

How can decompression of sigmoid volvulus be performed if this is the cause of large bowel obstruction?

Answer 21

by flexible sigmoidoscopy

Question 22

What type of intervention do the majority of patients with large bowel obstruction require?

Answer 22

surgical intervention - 70%

laparoscopic or open colonic resection

Question 23

What type of surgical intervention may be required for large bowel obstruction?

Answer 23

primary anastamosis or stoma formation

Question 24

When might palliative care be appropriate for the management of large bowel obstruction?

Answer 24

patients with malignant large bowel obstruction who are not candidates for surgery

Question 25

What type of surgical intervention may be performed for paliative purposes?

Answer 25

palliative stenting of the obstruction can be performed to help relieve symptoms

Question 26

What are 2 situations when conservative management may be appropriate in large bowel obstruction?

Answer 26

1. partial bowel obstruction cases
2. complete bowel obstruction with nos signs of ischaemia/necrosis or signs of clinical deterioration

Question 27

What are 3 ways that faecal impaction can be managed?

Answer 27

1. manual disimpaction
2. distal softening/washout with enemas or suppositories
3. proximal softening/washout with oral solutions such as polyethylene glycol (Movicol) or sodium phosphate

Question 28

Which type of medication is especially contraindication in complete mechanical bowel obstruction?

Answer 28

peristalsis-inducing medication e.g. metoclopramide

Question 29

Which type of analgesics may be most useful in bowel obstruction?

Answer 29

IV diclofenac - anti-spasmodic

Question 30

What are 2 examples of anti-emetics which can be used in bowel obstruction?

Answer 30

ondansetron, promethazine