Bowel obstruction

Question 1

What is bowel obstruction?

Answer 1

Mechanical blockage of the bowel whereby a structural pathology physically blocks the passage of intestinal contents

Question 2

What happens after the bowel segment is occluded?

Answer 2

Gross dilatation of the proximal limb of bowel, increased peristalsis and increased secretion of fluid into the bowel, meaning urgent fluid resuscitation is needed

Question 3

What is a closed loop obstruction?

Answer 3

If there is a second obstruction proximally e.g. volvulus or in large obstruction with competent ileocaecal valve

Question 4

What is the problem with a closed loop bowel obstruction?

Answer 4

will continue to distend, stretch and then become ischaemic and perforate

Question 5

What is functional obstruction/paralytic ileus?

Answer 5

When the bowel is not mechanically blocked but does not work properly due to inflammation, electrolyte derangement or recent surgery

Question 6

What is the most common cause of bowel obstruction in small bowel?

Answer 6

Adhesions or hernia

Question 7

What is the most common cause of bowel obstruction in the large bowel?

Answer 7

Malignancy, diverticular disease and volvulus

Question 8

What are some intraluminal causes of bowel obstruction?

Answer 8

gallstone ileus, ingested foreign body, faecal impaction

Question 9

What are some mural causes of bowel obstruction?

Answer 9

Carcinoma, inflammatory strictures, intussusception, diverticular strictures, meckels diverticulum and lymphoma

Question 10

What are some extra mural causes of bowel obstruction?

Answer 10

Hernias, adhesions, peritoneal metastasis, volvulus

Question 11

What are the clinical features of bowel obstruction?

Answer 11

Abdominal pain (colicky and crampy) Vomiting, abdominal distension and absolute constipation

Question 12

What is the vomit usually like in bowel obstruction?

Answer 12

Initially gastric contents, then becomes bilious and then faeculent

Question 13

If an obstruction is more distal, what clinical feature would be present?

Answer 13

constipation

Question 14

If an obstruction is more proximal what clinical features would be present?

Answer 14

Vomiting

Question 15

If bowel obstruction is present what would be felt on examination?

Answer 15

Underlying cause may be present, abdominal distension, palpate for focal tenderness including guarding and rebound tenderness

Question 16

What would percussion reveal in bowel obstruction?

Answer 16

tympanic sound

Question 17

What would auscultation of bowel obstruction reveal?

Answer 17

tinckling bowel sounds

Question 18

Do patients with bowel obstruction always how guarding and rebound tenderness?

Answer 18

No unless there is ischaemia

Question 19

What are the differential diagnosis for bowel obstruction?

Answer 19

Paralytic ileus, toxic megacolon and constipation

Question 20

What investigations are needed for bowel obstruction?

Answer 20

Urgent bloods and venous blood gas to look for ischaemia (high lactate) and metabolic derangements, CT scan with contrast of the abdomen

Question 21

Why do a CT with contrast of abdominal X-ray for bowel obstruction?

Answer 21

more sensitive, can differentiate between mechanical and pseudo obstruction, can demonstrate the site and cause of obstruction and may demonstrate metastases

Question 22

What would the signs of a small bowel obstruction be on a AXR?

Answer 22

Dilated bowel of more than 3cm, central abdominal location, valvulae conniventes visible- lines completely crossing the bowel

Question 23

What would the signs of a large bowel obstruction be on a AXR?

Answer 23

Dilated bowel of more than 6cm or 9 if caecum, peripheral location, haustral lines visible- lines not completely crossing the bowel

Question 24

What other imaging technique can be used for bowel obstruction?

Answer 24

contrast fluoroscopy if caused by adhesions from surgery

Question 25

What is the management for bowel obstruction?

Answer 25

Fluids, NBM, urinary catheter, anaglesia, water soluble contrast study, surgical management

Question 26

When would surgery be done in bowel obstruction?

Answer 26

if ischaemia or closed loop bowel obstruction, small bowel obstruction in a patient with a virgin abdomen, cause that needs surgery, if patient fails to improve conservatively, usually a laparotomy

Question 27

What are some complications of bowel obstruction?

Answer 27

Bowel ischaemia, bowel perforation and faecal peritonitis, dehydration and renal impairment

Question 28

What shape is sigmoid volvulus?

Answer 28

Coffee bean

Question 29

How many hours that contrast does not reach the colon would mean it is unlikely to resolve by itself?

Answer 29

4 hours