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GI and General surgery > Intestinal obstruction > Flashcards

Intestinal obstruction Flashcards

1
Q

What is the definition of intestinal obstruction?

A

Failure of downward passage of intestinal contents

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2
Q

What is meant by dynamic intestinal obstruction?

A

There is increasing peristalsis working against an obstructing agent

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3
Q

What is adynamic intestinal obstruction?

A

Peristalsis is absent or ineffective and there are no effective propulsive waves

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4
Q

What is a simple obstruction?

A

Obstruction of the intestinal lumen without interference with its blodd supply

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5
Q

What happens above the site of obstruction in someone with a simple obstruction?

A

Peristalsis + distention (due to gas, GI content and fluid build up)

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6
Q

What are causes of death in simple bowel obstruction?

A
  • Fluid & electrolyte imbalance
  • Peritonitis
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7
Q

What is strangulation?

A

Intestinal obstruction with persistent interference of the blood supply

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8
Q

What are causes of intestinal strangulation?

A
  • Strangulated hernia
  • Intussuception
  • Adhesive intestinal obstruciton
  • Volvulus
  • Vascular occlusions
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9
Q

What are the pathophysiological consequences of strangulation?

A
  • Venous return is impaired - strangulated bowel and its mesentery look congested
  • Serosanguinous fluid formation - accumulated inside the peritoneal cavity
  • Arterial supply is impaired - colour of the affected segment becomes black
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10
Q

What are causes of death in strangulation?

A
  • Peritonitis due to perforation
  • Hypovolaemic shock
  • Sepsis
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11
Q

What is a closed loop obstruction?

A

When some part of the gut is closed at both ends - THIS IS DANGEROUS

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12
Q

What are causes of small bowel obstruction?

A
  • Adhesions
  • Hernias
  • Malignant tumours
  • Crohn’s disease
  • Intussusception
  • Gallstone ileus
  • Paralytic ileus
  • Miscellaneous (bezoars)
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13
Q

What is the most common cause of small bowel obstruction?

A

Adhesions

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14
Q

What are abdominal adhesions?

A

Adhesions are bands of ‘scar’ tissue in various degrees of development. They are part of a normal intra-abdominal repair process following a variety of insults

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15
Q

What is the pathophysiology behind abdominal adhesion formation?

A

Peritoneum is ‘injured’ -> reparative process similar to that seen following the formation or in prevention of a thrombus.

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16
Q

What types of internal hernias can occur which can lead to small bowel obstruction?

A
  • Paraduodenal
  • Transmesocolic
  • Transmesenteric
  • Omental
  • Retroanastomotic - bowel is trapped behind a surgical anastomosis
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17
Q

What types of benign tumours of the small intestine can cause SBO?

A
  • Hyperplastic polyps
  • Lipomas
  • Adenomas - including Peutz-Jeghers polyps
  • G/I stromal tumors
  • Hemangiomas
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18
Q

What secondary malignancies can present as SBO?

A
  • Ovarian
  • Stomach
  • Pancreas
  • Colonic
  • Malignant melanoma
  • Lung
  • Breast
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19
Q

How can crohn’s disease lead to SBO?

A

Can cause strictures. May also have adhesions from previous surgeries

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20
Q

What are causes of paralytic ileus?

A
  • Post surgery especially for peritoneal sepsis
  • Drugs - TCAs
  • Spinal injury
  • Electrolyte imbalance - hypokalaemia, hyponatraemia, uraemia
  • Extensive handling of the bowel at operation
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21
Q

How does paralytic ileus increase the risk of adhesion formation?

A
  • Intestinal segments have more prolonged contact, which allows fibrous adhesions to form
  • Intestinal distention causes serosal injury and ischemia
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22
Q

What are the pathophysiological consequences of small bowel obstruction?

A
  • Proximal dilatation of intestine - due to accumulation of GI secretions and swallowed air
  • Stimulation of columnar cell secretory activity - increase in intra-lumenal fluid
  • Increased peristalsis above and below the obstruction -
  • Early frequent loose stools and flatus
  • Increased intraluminal pressure
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23
Q

What is the result of small bowel obstruction in terms of fluid balance?

A

Hypovolaemia - due to:

  1. Compression of mucosal lymphatics -> lymphoedema of the bowel wall
  2. High intraluminal hydrostatic pressures -> increased hydrostatic pressure in the capillary beds
  3. Massive loss into the third space - fluid, electrolytes, and proteins (into lumen)
  4. Vomiting + loss of normal fluid intake
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24
Q

How does intestinal obstruction affect intestinal flora?

A
  • Proliferation proximal to obstruction
  • Microvascular changes in bowel wall -> Translocation of bacteria to mesenteric lymph nodes
  • Resultant bacteraemia
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25
Q

What are symptoms of small bowel obstruction?

A
  • Pain
  • Vomiting
  • Abdominal distention
  • Absolute constipation - late symptom
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26
Q

What are signs of SBO?

A
  • Features on inpection - surgical scars, visible peristalsis
  • Dehydration/Signs of shock
  • Abdominal distention
  • Bowel sounds
    • Increased/borborygmus - early dynamic
    • Decreased/absent - paralytic and late mechanical
  • May have signs of peritonism
  • Empty rectum on PR
  • May have herniation - non-reducible
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27
Q

What are the characteristic features of abdominal pain in intestinal obstruction?

A

Generalized abdominal colicky pain - Each attack lasts for few minuets then gradually disappears, with periouds of relief in between

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28
Q

When is distention less prominent in SBO?

A

When the obstruction is more proximal

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29
Q

When is distention more prominent in SBO?

A

In distal obstruction

30
Q

How does the timing of vomiting roughly indicate where a SBO might be?

A

The more proximal the obstruction, the earlier vomiting will occur:

  • Jejunal Obstruction - Vomiting occurs with the first and each attack of pain
  • Ileal Obstruction - Vomiting is delayed for few hours; then it occurs with each attack of pain
31
Q

If vomiting occured early on in someone with suspected SBO, what might this suggest about where the problem is in the small intestine?

A

High - e.g. jejunal obstruction

32
Q

If feculent vomiting occured late after someone presented with abdominal pain and marked abdominal distention, where might you suspect the obstruction is occuring?

A

Low - e.g. ileum

33
Q

If someone had jejunal obstruction, how distended would their abdomen be?

A

Minimally distended

34
Q

If someone had ileal obstruction, how much abdominal distention might they have?

A

Prominent central distention

35
Q

If someone had distention of the flanks, what might this indicate about where the obstruction is occuring?

A

Colonic distention only - LBO with competent ileocaecal valve

36
Q

If someone had generalised distention of the abdomen, what might this indicate as to where the obstruction is occuring?

A

Distended small bowel & colon - LBO with incompetent ileocaecal valve

37
Q

What featuress would make you think that someone had a stangulated obstruction?

A
  • Pain - more severe and never completely absent in between the attacks
  • Shock - usually present and progressive
  • Tenderness & Rigidity - Localized tenderness & rebound tenderness
  • Tense, tender, irreducible, non-expansile external hernia
38
Q

What are symptoms of LBO?

A
  • Absolute constipation
  • Lower abdominal pain
  • Vomiting a late manifestation
  • Features of ischaemia/strangulation
    • Acute toxicity
    • Fever
    • Chills
    • Hypotension
    • Confusion
39
Q

What signs can occur in LBO?

A
  • Features on inpection - surgical scars, visible peristalsis
  • Dehydration/Signs of shock
  • Abdominal distention - Flanks/generalised
  • Abdominal Mass
  • Bowel sounds
    • Increased/borborygmus - early dynamic
    • Decreased/absent - paralytic and late mechanical
  • May have signs of peritonism
  • Tender LIF - diverticular disease
  • Tender RIF +/- mass - impending ischaemia
  • PR - rectal mass, blood, mucus
  • May have herniation - non-reducible
40
Q

What are the 2 most common causes of SBO?

A

Adhesions and hernias

41
Q

What are causes of large bowel obstruction?

A
  • Colon cancer
  • Constipation
  • Diverticular stricture
  • Volvulus
42
Q

What investigations would you perform if you suspected intestinal obstruction?

A
  • Bedside - NEWS score, Fluid status and urine output
  • Bloods - FBC, U+E’s, LFTs, consider ABG
  • Imaging - AXR, Erect CXR, Gastrografin follow through/enema (LBO), Consider CT
43
Q

What might you see on AXR in someone with suspected small bowel obstruction?

A
  • Dilated loops proximal to the obstruction - predominantly central dilated loops
  • Valvulae conniventes are visible
  • Air-fluid levels if the study is erect
  • Gasless bowel
    • Partial: gas throughout the abdomen and into the rectum.
    • Complete: no distal gas, and staggered air-fluid levels.
44
Q

What might you see on CXR in someone with an intestinal obstruction?

A

Free air under the diaphragm - due to perforation

45
Q

What is important to include in your examination of someone with features of intestinal obstruction?

A

PR and hernial orifice exam

46
Q

What is a gastrografin follow through study?

A

Involves administration of contrast material into the stomach. The subsequent assessment of degree of passage of this material, using serial x-rays, can provide information regarding the presence and location of the obstruction within the GI tract:

  • Partial SBO - medium passes into rectum.
  • Complete SBO - medium does not pass into rectum and is held up at site of obstruction.
47
Q

What might you find on U+E’s in someone with bowel obstruction?

A
  • Electrolyte imbalance - hyponatraemia, hypokalaemia
  • Hyperuraemia - Renal failure
48
Q

What might you use a gastrografin enema to look for?

A

Lower bowel obstruction

49
Q

What might you use a CT to look for in the context of bowel obstruction?

A
  • Confirm the diagnosis if transition point is seen
  • Identify the level (SBO/LBO)
  • Find the cause
  • Staging in obstruction secondary to malignancy
50
Q

What are causes of obstruction in newborn babies?

A
  • Imperforate anus
  • Congenital atresia/stenosis of the gut
  • Volvulus
51
Q

What is the most common cause of obstruction in a child age 3-12 months old?

A

Intussuception

52
Q

How would you manage someone with complete/complicated/stangulated SBO?

A
  • ABCDE - give 100% oxygen
  • NG decompression
  • IV fluids
  • Analgesia
  • Investigations - AXR, erect CXR, Bloods, monitoring/fluid status
  • Surgery/Emergency surgery - laparoscopy
    • Stangulation is an emergency
53
Q

What are indications for early surgery in bowel obstruction?

A
  • Obstructed hernia
  • Suspected strangulation
  • Small bowel obstruction in a ‘virgin abdomen’
  • Failure of conservative Rx in adhesive SBO
  • Obstructing tumours on CT
54
Q

How would you manage someone with complete/complicated/stangulation obstruction who wasn’t fit for surgery?

A
  • ABCDE
  • NG decompression + fluid resus
  • Antiemetics
  • Antispasmodics
55
Q

How would you manage partial SBO?

A
  • ABCDE
  • NG decompression
  • IV fluid resus
  • Analgesia
  • Anti-emetics
  • Consider surgery if not resolved within 48-72 hrs
56
Q

What are the differences in radiological appearence of the jejunum, ileum and colon?

A
57
Q

How would you treat intussusception in an adult?

A

Laparotomy - resection +/- anastamosis

58
Q

What are the different types of volvulus that can occur?

A
  • Volvulus neonatorum
  • Volvulus of small intestine
  • Caecal volvulus
  • Sigmoid volvulus
59
Q

What are features of a sigmoid volvulus?

A
  • Sudden left sided abdo pain
  • Adbo distention
  • Absolute constipation
60
Q

How would you manage a sigmoid volvulus?

A
  • General management
  • Surgery
    • Emergency: Untwisting by flexible sigmoidoscopy -> Sigmoid resection in fit patients
    • Failed sigmoidoscopy -> open surgery
61
Q

If someone was found to have a large bowel obstruction on AXR, what investigation would you consider doing next?

A

Gastrografin enema - determine whether carcinoma, ogilives syndrome or diverticular disease

62
Q

If someone was found to have free gas under the abdomen on AXR, How would you manage them?

A

Surgery

63
Q

What are contraindications for primary anastamosis?

A
  • Poor bowel preparation (on-table lavage *may be indicated)
  • Friable bowel
  • Circulatory instability
  • Synchronous or multiple tumours**
  • Peritonitis present
  • Immunocompromised patient
  • Previous radiation (often pelvic)
  • Pelvic abscess present (debatable)
64
Q

What is OGilvie syndrome?

A

Clinical syndrome with symptoms, signs & AXR appearance of LBO but with no identifiable mechanical obstruction

65
Q

What are predisposing factors to developing Ogilivie syndrome?

A
  • Puerperium
  • Pelvic surgery
  • Trauma
  • Cardiorespiratory disorder
  • Neurological disorder
66
Q

How do individuals with Ogilvie syndrome present?

A

With features of mechanical bowel obstruction

67
Q

How would you manage Ogilvie syndrome?

A
  • Neostigmine
  • Colonoscopic decompression
68
Q

What are the key things that you need to establish in suspected bowel obstruction?

A
  1. Is it small or large bowel?
  2. Is it dynamic/adynamic (ileus vs mechanical)?
  3. Is it simple/closed loop/strangulated?
69
Q

What is the cardinal sign of a strangulated obstruction?

A

Peristonism

70
Q

What is the pathophysiology of Ogilvie’s syndrome?

A

Most likely caused by a disturbance of the autonomic nervous system:

  • Reflex sympathetic stimulation inhibiting colon and/or
  • Interruption of parasympathetic influence of S2-S4

This leads to colonic dilatation and colonic atony

71
Q

What mnemonic can be used to remember the main symptoms of obstruction?

A

PC D+V

  • Pain
  • Vomiting
  • Distention
  • Constipation
72
Q

What mnemonic can be used to remember the causes of small bowel obstruction?

A

SHAVIT

  • Stones (gall stone ileus )
  • Hernias (always examine hernial orifices!)
  • Adhesions (can occur very early and very late after surgery)
  • Volvulus
  • Intusssusception / IBD
  • Tumour (1º adenocarcinomas rare in small bowel)

**Adhesions and hernias are the commonest causes of small bowel obstruction and should be considered before more unusual causes.

GI and General surgery (44 decks)

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