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z - Gastrointestinal > Bowel Obstruction > Flashcards

Bowel Obstruction Flashcards

1
Q

What does the colloquial term bowel obstruction usually refer to?

A

A mechanical blockage of the bowel, whereby a structural pathology physically blocks the normal passage of the intestinal contents

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2
Q

What % of acute abdomen cases are found to have a bowel obstruction?

A

15%

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3
Q

What is a functional bowel obstruction also known as?

A

A paralytic ileus

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4
Q

What happens in a functional bowel obstruction?

A

The bowel is not mechanically blocked, but does not work properly

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5
Q

Give 3 examples of causes of functional bowel obstruction?

A
  • Inflammation
  • Electrolyte derangement
  • Recent surgery
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6
Q

How can a functional bowel obstruction be differentiated from a mechanical one clinically?

A

In a functional bowel obstruction, bowel sounds are absent, and the pain tends to be less

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7
Q

What happens once a bowel segment has become occluded?

A

There is gross dilation of the proximal limb of the bowel, which in turn results in an increased peristalsis of the bowel

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8
Q

What does increased peristalsis of the bowel as a result of occlusion of a bowel segment lead to?

A

Secretion of large amounts of electrolyte rich fluid into the bowel

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9
Q

What is the clinical relevance of the secretion of large amounts of electrolyte rich fluid into the bowel in an obstruction?

A

It means urgent fluid resuscitaiton and close attention to fluid balance is essential

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10
Q

What is a simple bowel obstruction?

A

One where there is one obstructing point, and no vascular compromise

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11
Q

What is a ‘closed loop’ obstruction?

A

When there is a second obstruction proximally

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12
Q

When might a closed loop obstruction occur?

A
  • If the obstruction is due to a twist in the bowel
  • In a large bowel obstruction if the ileocaecal valve is competent
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13
Q

Why is a closed loop bowel obstruction a surgical emergency?

A

Because the bowel will continue to distend, stretching the bowel until it becomes ischaemic and perforates

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14
Q

What happens in a strangulated obstruction?

A

The blood supply is compromised

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15
Q

How does a strangulated obstruction present clinically?

A
  • The patient is more ill than you would expect
  • There is sharper, more constant, and localised pain
  • Peritonism is the cardinal sign, but there may be fever, increased WCC, and other signs of mesenteric ischaemia
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16
Q

What are the causes of small bowel obstruction?

A
  • Adhesions
  • Hernias
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17
Q

What are the causes of large bowel obstruction?

A
  • Colon cancer
  • Constipation
  • Diverticular stricture
  • Volvulus
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18
Q

What are the categories of causes of bowel osbtruction?

A
  • Intraluminal
  • Mural
  • Extramural
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19
Q

What are the causes of intraluminal bowel obstruction?

A
  • Gallstone ileus
  • Ingested foreign body
  • Faecal impaction
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20
Q

What are the mural causes of bowel obstruction?

A
  • Carcinoma
  • Inflammatory strictures
  • Intussusception
  • Diverticular strictures
  • Meckel’s diverticulum
  • Lymphoma
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21
Q

What are the extramural causes of bowel obstruction?

A
  • Hernias
  • Adhesions
  • Peritoneal metastasis
  • Volvulus
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22
Q

What are the symptoms of bowel obstruction?

A
  • Abdominal pain
  • Vomiting
  • Abdominal distention
  • Absolute constipation
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23
Q

Describe the abdominal pain in bowel obstruction

A

Colicky or cramping in nature

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24
Q

What is the abdominal pain in bowel obstruction secondary too?

A

Bowel peristalsis

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25
Q

What abdominal pain in bowel obstruction is a red flag that ischaemia may be developing?

A

Any pain that was originally colicky, and is now constant in nature or worse on movement

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26
Q

Describe the vomiting in bowel obstruction?

A

It is initially of gastric contents, before becoming bilious and eventually faeculent

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27
Q

What is absolute constipation?

A

Failure to pass flatus and faeces

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28
Q

What are the features of a small bowel obstruction?

A
  • Vomiting occurs early
  • Distention is less
  • The pain is higher in the abdomen
29
Q

How does the pain differ in small and large bowel osbtruction?

A

The pain is more constant in large bowel obstruction

30
Q

What plays a key role in differentiating small and large bowel obstruction?

A

AXR

31
Q

What examination signs may be seen in a bowel obstruction?

A
  • Abdominal distention
  • Tenderness
  • Tympanic sound on percussion
  • Tinkling bowel sounds on auscultation
  • May show signs of underlying cause
32
Q

Describe the tenderness in bowel obstruction

A

Patients with bowel obstruction may be uncomfortable on palpation due to discomfort from pressing on distended abdomen, but should be no focal tenderness, guarding, or rebound tendernes

33
Q

What does focal tenderness, guarding, or rebound tenderness on examination on bowel obstruction indicate?

A

Ischaemia is developing

34
Q

What signs of an underlying cause may be seen on examination?

A
  • Surgical scars
  • Cachexia from malignancy
  • Obvious hernia
35
Q

What should be assessed for in a patient with bowel obstruction?

A

Signs of dehydration and sepsis

36
Q

What investigations should be done in bowel obstruction?

A
  • Blood tests
  • VBG
  • Imaging
37
Q

What blood tests should be done in bowel obstruction?

A
  • FBC
  • CRP
  • U&E
  • G&S
38
Q

What may be found on U&Es in bowel obstruction?

A
  • Hypokalaemia
  • High urea
39
Q

Why may VBGs be useful in bowel obstruction?

A
  • Evaluate signs of ischaemia
  • Immediate assessment of any metabolic derangement
40
Q

What signs of ischaemia can be detected on a VBG?

A

High lactate

41
Q

What might cause metabolic derangement in bowel obstruction?

A
  • Dehydration
  • Excessive vomiting
42
Q

What imaging is done in bowel obstruction?

A
  • CT imaging
  • Plain AXR
  • Contrast fluroscopy
43
Q

What is the imaging modality of choice in suspected bowel obstruction?

A

CT imaging

44
Q

What are the advantages of CT imaging over AXR in bowel obstruction?

A
  • More sensitive for bowel obstruction
  • Can differentiate between mechanical obstruction and pseudo-obstruction
  • Can demonstrate the site and cause of obstruction, and so are useful for operative planning
  • May demonstrate the presence of metastases if caused by malignancy
45
Q

When are plain AXRs used in the investigation of bowel obstruction?

A

They are used in some settings in the initial investigations

46
Q

Why might an erect chest x-ray be useful in the investigation of bowel obstruction?

A

To assess for free air under the diaphragm, which present in perforation

47
Q

What is considered to be dilated small bowel on AXR?

A

>3cm

48
Q

How can small bowel obstruction be differentiated from large bowel obstruction on AXR?

A
  • Small bowel obstruction has central abdominal location. Large bowel obstruction is in peripheral location
  • Small bowel obstruction has valvulae conniventes visible, which completely cross the bowel. Large bowel obstruction have haustral lines visible, which do not completely cross the bowel
49
Q

What is considered to be dilated large bowel on AXR?

A

>6cm, or >9cm on caecum

50
Q

What is the use of contrast fluroscopy useful in bowel obstruction?

A
  • Useful in small bowel obstruction caused by adhesions from previous surgery
  • Has been shown to reliably predict wether or not obstruction will settle
51
Q

What is the definitive management of bowel obstruction dependant on?

A
  • The aetiology
  • Whether it has been complicated by bowel ischaemia, perforation, and/or peritonism
52
Q

When will patients with bowel obstruction require urgent surgery?

A
  • Closed loop bowel obstruction
  • Evidence of ischaemia
53
Q

What evidence of ischaemia may be present in bowel obstruction?

A
  • Pain worsened by movement
  • Focal tenderness
  • Pyrexia
54
Q

Why is the management of fluid important in bowel obstruction?

A

Patients with bowel obstruction are often very fluid deplete

55
Q

How is fluid managed in bowel obstruction?

A
  • All patients need urgent fluid resuscitation
  • Need to pay careful attention to fluid balance, may require urinary catheter
56
Q

How is bowel obstruction managed in the absence of signs of ischaemia or strangulation?

A

Conservatively

57
Q

What is the conservative management of bowel obstruction often termed?

A

‘Drip and suck’

58
Q

What does the conservative management of bowel obstruction include?

A
  • NBM, and insertion of nasogastric tube to decompress bowel
  • IV fluids and correction of any electrolyte disturbance
59
Q

What should be done when considering when to employ conservative management for a bowel obstruction?

A

A water-soluble contrast study

60
Q

How will a water soluble contrast study aid in your decision wether to attempt conservative management of a bowel obstruction?

A

If the contrast does not reach the colon by 6 hours, it is very unlikely that the obstruction will resolve, and the patient should be taken to theatre

61
Q

What is the success rate for conservative treatment for adhesional small bowel obstruction?

A

80%

62
Q

What kind of bowel obstruction rarely settles without surgery?

A
  • Large bowel obstruction
  • Small bowel obstruction in a patient who has not had previous surgery
63
Q

When is the surgical management of a bowel obstruction indicated?

A
  • Suspicion of intestinal ischasemia or closed loop bowel obstruction
  • Small bowel obstruction in patient with virgin abdomen
  • Causes that require surgical correction
  • If patient fails to improve with conservative measures after 48 hours
64
Q

Give two examples of causes of bowel obstruction that require surgical correction

A
  • Strangulated hernia
  • Obstructing tumour
65
Q

What will the nature of surgical management in bowel obstruction depend on?

A

Underlying cuse

66
Q

What does the surgical management of a small bowel obstruction generally involve?

A

A laparotomy

67
Q

What is often the consequence of a bowel resection if required for a bowel obstruction?

A

Re-joining of the obstructed bowel is often not possible, and a stoma may be necessary

68
Q

What are the complications of bowel obstruction?

A
  • Bowel ischaemia
  • Bowel perforation, leading to faecal peritonitis
  • Dehydration and renal impairment

z - Gastrointestinal (6 decks)

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