Bowel Obstruction

Question 1

function of small bowel?

function of large bowel?

Answer 1

nutrient absorption

water absorption

Question 2

four main clinical features of bowel obstruction

Answer 2

distension
constipation
vomiting
abdominal pain

Question 3

vomiting more profuse in small or large bowel obstructio?

Answer 3

small bowel

Question 4

is the pain sudden or gradual?

character of pain ?

location?

Answer 4

sudden onset of pain

colicky/constant

central

Question 5

what sort of bowel sounds do you get as obstruction progresses leading to abdominal distension

Answer 5

tinkling BS

Question 6

how can you determine if it is small or large bowel obstruction?

Answer 6

small bowel

• vomiting occurs early
• less distension
• pain higher in abdomen and colicky

large bowel
- pain is more constant

Question 7

small bowel obstruction on AXR?

Answer 7

centrally dilated + see in dilated bowel section there is valvulae conniventes (cross the lumen)

Question 8

large bowel obstruction on AXR:

Answer 8

peripheral gas shadows and and see large bowel haustra that don’t cross the lumen.

Question 9

how can you tell if it is a functional/ileus or a mechanical bowel obstruction?

Answer 9

functional = reduced bowel motility - absent BS + NO PAIN

mechanical = pain + tinkling BS

Question 10

difference between simple/closed loop/strangulated bowel obstruction?

which one of the three presents with a more sharp constant pain?

Answer 10

simple = one obstructing point + no vascular compromise

closed loop = obstruction at two points + vascular compromise, at risk of perforation due to forming a loop of distended bowel

strangulated bowel obstruction = blood supply is compromised, sharp + constant pain - more localised with peritonism

Question 11

where does closed loop bowel obstruction normally occur?

Answer 11

caecum

Question 12

is sigmoid volvulus simple, closed loop or strangulated obstruction

Answer 12

closed loop but at risk of becoming strangulated

Question 13

common causes of small bowel obstruction?

Answer 13

adhesion
neoplasms
hernias

Question 14

what is an adhesion

Answer 14

fibrous band that forms as a result of injury during surgery - internal scar tissue

Question 15

common causes of large bowel obstruction

Answer 15

colon cancer
diverticular stricture
volvulus (often sigmoid or caecal)

Question 16

where are diverticular strictures most commonly found

Answer 16

sigmoid

Question 17

what is sigmoid volvulus?

commonly occurs in which patients?

how is it managed if no signs of avascular necrosis?

how is it managed if there is gangrenous tissue?

Answer 17

when bowel twists on its mesentery producing severe obstruction -

occurs in elderly, constipated patient.

insertion of flatus tube or sigmoidoscopy

sigmoid colectomy

Question 18

what % of large bowel obstructions are due to cancer or diverticular stricture?

Answer 18

90%

Question 19

Management of strangulation and large bowel obstruction?

Answer 19

Surgery

Question 20

Management of ileus and small bowel obstruction?

Answer 20

can be managed conservatively initially

Question 21

Management of bowel obstruction is of ‘Drip and Suck’ lines similarly to pancreatitis

what is the initial Tx of bowel obstruction

Answer 21

o NBM
o IV fluids to rehydrate and correct electrolyte imbalance (vomit).
o Insert NGT (Ryle’s tube) to relieve gastric distension (to stop vomiting, + blockage partially improves as you rest the bowel as half the problem with bowel obstruction is the swelling/oedema around the obstruction).
o IV Analgesia, catheterize to monitor fluid balance.

Question 22

what % of bowel obstructions will be relieved by NBM, fluids, NGT + analgesia?

Answer 22

70%

Question 23

Some large bowel obstructions can be relieved by flexible sigmoidoscopy to unkink colon but risk of what?

Answer 23

Perforation

Question 24

what imaging do you do to identify cause and location of obstruction?

what can be given prior to this which may actually have mild therapeutic action?

Answer 24

CT Abdo

gastrografin

Question 25

what type of obstruction is a surgical emergency?

Answer 25

strangulation/closed loop

Question 26

what would indicate an immediate laparatomy?

Answer 26

if signs of peritonitis
OR
if caecum dilated >10

Question 27

complications?

where does perforation commonly occur?

Answer 27

perforation
abdominal abscess
peritonitis

caecum (as it’s the thinnest)