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Year 2 > Bowel Obstructions > Flashcards

Bowel Obstructions Flashcards

1
Q

Define intestinal obstruction

A

Arrest/Blockage on onward propulsion of intestinal contents

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2
Q

How are obstructions classified (4)

A
  1. According to site (Large bowel/small/gastric)
  2. Extent of luminal obstruction (partial or complete)
  3. According to mechanism (mechanical/true/functional)
  4. According to pathology (simple, closed loop, strangulation or intussusception)
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3
Q

What usually causes a complete luminal obstruction

A
  1. Volvulus = resulting in overflow and sickness
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4
Q

What is true mechanism of intestinal obstruction

A

INtraluminal or extraluminal obstruction

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5
Q

Give an example of a functional bowel obstruction

A
  1. Dynamic bowel due to the absence of normal peristaltic contractions, caused by abdo surgery or acute pancreatitis
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6
Q

What is intussusception

A

Part of an intestine folds into the next section of bowel

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7
Q

What tumours can cause obstruction of the lumen

A
  1. Carcinoma

2. Lymphoma

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8
Q

What is diaphragm disease

A

Formation of thin-walled strictures which narrow the lumen into a ‘pinpoint’

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9
Q

What usually causes diaphragm disease

A

NSAIDs

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10
Q

What is Meconium ileum

A

Content of bowel is sticky = blockage

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11
Q

What is gallstone ileum

A

Gallstone within lumen of small bowel

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12
Q

What inflammatory disease can cause bowel obstruction

A
  1. Crohn’s disease

2. Diverticulitis

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13
Q

Where does diveritulitis occur

A

Sigmoid colon

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14
Q

What is diverticulitis

A

Inflammation of the pouches (diverticula) in the large intestines

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15
Q

Where do diverticulas form

A

Where blood vessels penetrate

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16
Q

Describe how a diverticula forms

A
  1. In low fibre diets, colon tries to push harder to move things alone increasing pressure
  2. Pressure increase pushes mucosa through gaps = diverticula (outpouching)
  3. They get inflamed or burst
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17
Q

Consequences of diverticulitis (what conditions can it cause in the long-term)

A
  1. Acute peritonitis

2. Possible death

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18
Q

What neural disease can cause bowel obstruction

A
  1. Hirschsprung’s disease
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19
Q

What is Hirschsprung’s disease

A

In babies - no complete innervation of colon to rectum

Causes gut dilatation and filling of faeces which remains since no ganglion cells do peristalsis (obstruction)

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20
Q

How do adhesions cause bowel obstructions

A
  1. Sticking together of abdo structures to one another (e.g. bowel loops, omentums, other solid organs by fibrous tissues)
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21
Q

What is the most common cause of obstruction in adults

A

Adhesions

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22
Q

When are adhesions common

A

After surgery

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23
Q

How does adhesion cause obstruction

A

Usually free-moving intestines

When movement is limited by fibrous tissue, intestine can twist on themselves occluding blood supply or peristaltic movement

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24
Q

What kind of obstruction is a volvulus

A

Closed loop bowel

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25
Q

What carcinoma causes peritoneal tumours to form

A

Ovarian carcinomas

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26
Q

What are signs of any bowel obstructions

A

Tinkling bowel sounds

Tympanic percussion

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27
Q

What usually causes SMALL BOWEL obstruction

A

A previous surgery

OR

Crohn’s disease

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28
Q

Main mechanisms that cause SBO

A
  1. ADHESIONS
  2. Hernias

Any mechanical obstructions

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29
Q

What surgeries in particular will cause adhesions and thus small bowel obstructions

A

Pelvic, gyro and colorectal surgery

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30
Q

Long-term effect of hernias on the GI tract

A

STRANGULATION

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31
Q

How does obstruction effect the small bowel

A
  1. Bowel distension above block
  2. Increased secretion of fluid into distended bowel

Proximal dilatation above block:

  1. Increased secretions and swallowed air into small bowel
  2. More dilatation results in decreased absorption and mucosal wall oedema
  3. Increased pressure with the intramural vessels becoming compressed resulting in ischaemia or perforation
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32
Q

What happens if small bowel disease is left untreated

A
  1. Ischaemia
  2. Necrosis
  3. Perforation
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33
Q

Clinical presentation of SBO

A
  1. Pain (colicky) then pain becomes higher in abdomen than in LBO
  2. Vomiting following pain (occurs earlier in SBO than LBO)
  3. Less distention to LBO
  4. Nausea + anorexia
  5. Tenderness suggests strangulation and urgent surgery is required
  6. Constipation with no passage of wind
  7. Increased bowel sounds
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34
Q

Four diagnostics for SBO

A
  1. Abdo X-ray
  2. Examination of hernia orifices and rectum
  3. FBC
  4. GOLD STANDARD - CT
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35
Q

What does a CT show in SBO

A

Localise lesions

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36
Q

Role of AXR in SBO

A
  1. Shows central gas shadows that completely cross the lumen and no gas in the large bowel
  2. Distended loops of bowel proximal to obstruction
  3. Fluid levels seen
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37
Q

How is SBo treated

A
  1. Fluid resus
  2. Bowel decompression
  3. Analgesia and antiemetic
  4. Antibiotics
  5. Surgery (remove obstruction via laparotomy)
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38
Q

What are antiemetics

A

Treat vomiting and nausea

39
Q

How long does it take for LBOs to present

A

5 days until symptoms occur as it has a larger lumen

40
Q

Why does it take a while for symptoms to occur and why is it rare for LBOs to occur

A
  1. Larger lumen

2. Circular and longitudinal muscles all large bowel to distend much greater

41
Q

What usually causes LBO

A

Colorectal malignancies

rarely volvulus

42
Q

What part of the colon dilates in LBO

A

The colon proximal to obstruction dilates

43
Q

How does this effect blood flow and colonic pressure in LBO (dilatation)

A

Increases colonic pressure

Decreased mesenteric blood flow = mucosal oedema

44
Q

What is mucosal oedema

A

Transudation of fluid and electrolytes from the lumen

45
Q

How can dilatation of the LBO effect arterial blood supply

A

Mucosal oedema caused can ischaem the arteries and cause mucosal ulceration

46
Q

Result on mucosal ulceration on GI

A

Full thickness necrosis and perforation

47
Q

How does sepsis effect the GI tract i LBO

A

Bacterial translocation

48
Q

What happens in a colonic volvulus

A
  1. There is axis rotation based of mesentery and a 360 degree twist resulting in a closed loop obstruction
49
Q

How does a colonic volvus effect pressure/blood flow and contents of the GI tract in LBO

A
  1. Fluid and electrolytes shift into closed loop
  2. Increased pressure and tension in the loop causes impaired colonic blood flow
  3. Ischaemia, necrosis and perforation of the bowel loop soon follows if untreated
50
Q

CLinical presenttation of LBO

A
  1. Abdo pain
  2. Abdo distention
  3. Bowel sounds normal than increased then quiet later
  4. Palpable mass
  5. Late vomiting (faecal-like)
  6. Constipation
  7. Fulllness/bloating/Nausea
51
Q

How to diagnose LBO

A
  1. Digital rectal exam
  2. FBCs
  3. AXR
  4. CT
52
Q

What do we look for in a digital rectal exam for LBO

A
  1. Empty rectum
  2. Hard stools
  3. Blood
53
Q

What would we look for in FBCs for LBO

A

Low Hb (Cause bloody stools)

54
Q

What would AXR show for LBO

A
  1. Peripheral gas shadows proximal to the blockage (in caecum not rectum) UNLESS PR examination is done
  2. Distended caecum and ascending colon
55
Q

How is LBO treated

A
  1. Aggressive fluid resus
  2. Bowel decompression
  3. Analgesia + antiemetic
  4. Antibiotics
  5. Surgery (removes obstruction done by laparotomy (open surgery)
56
Q

How are obstructions in the LBO due to malignancy treated

A
  1. Colorectal stents followed by elective surgery
57
Q

What is pseudo-obstruction

A

Mimics obstruction but with no mechanical cause

58
Q

What usually causes pseudo-obstruction

A
  1. Intra-abdominal trauma
  2. Pelvic, spinal and femoral fractures
  3. Postoperative states
  4. Intra-abdominal sepsis
  5. Pneumonia
  6. Drugs (opiates)
  7. Metabolic disorders
59
Q

Clinical presentation of pseudo-obstruction

A

Progressive abdo distention and pain

60
Q

How is pseudo-obstruction diagnosed

A

Gas-filled large bowel

61
Q

How is pseudo-obstruction treated

A

Treat underlying problem

IV NEOSTIGMINE (

62
Q

What three types of bowel ischaemia are there

A
  1. Acute mesenteric ischaemia
  2. Chronic mesenteric ischaemia (intestinal angina)
  3. Ischaemic colitis (Chronic colonic ischaemia)
63
Q

What blood supplies the colon

A
  1. Inferior superior mesenteric arteries
64
Q

What are watershed areas

A

Splenic flexure

Caecum

65
Q

What does AF with abdo pain indicate (conditions wise)

A

Mesenteric Ischaemia

66
Q

What part of the GI tract is effected by acute mesenteric ischaemia

A

Small bowel

67
Q

What is the most common cause of acute mesenteric ischaemia

A

Superior mesenteric artery thrombosis

68
Q

How does AF cause acute mesenteric ischaemia

A

Superior mesenteric artery embolism

69
Q

In which patients is mesentery vein thrombosis a cause for acute mesenteric ischaemia

A

Younger patients

70
Q

What other factor causes acute mesenteric ischaemia

A

Non-occlusive diseases

71
Q

Clinical presentation of acute mesenteric ischaemia

A
  1. Acute severe abdo pain (constant, central at right iliac fossa)
  2. No abdo signs
  3. Rapid hypovolaemia resulting in shock
72
Q

How is acute mesenteric ischaemia diagnosed

A
  1. Bloods
  2. AXR
  3. Laparotomy
  4. CT/MRI angiography
73
Q

What would we see in blood tests for acute mesenteric ischaemia

A

Raised Hb due to plasma loss
Raised WBC
Persistent metabolic ACIDOSIS

74
Q

What would we see in AXR for acute mesenteric ischaemia

A
  1. Used to rule out other pathologies and gads-less abdomen
75
Q

What is a laparotomy

A
  1. Surgical procedure -> cut into abdo wall -> access abdo cavity
76
Q

Why is a laparotomy used for acute mesenteric ischaemia

A

To make diagnosis

See necrotic bowel

77
Q

How is acute mesenteric ischaemia treated

A
  1. Fluid resus
  2. Antibiotics (IV GENTAMICIN + METRONIDAZOLE)
  3. IV HEPARIN to reduce clotting
  4. Surgery to remove dead bowel
78
Q

Complications of treating acute mesenteric ischaemia

A
  1. Septic peritonitis
  2. Systemic inflammatory response syndrome progressing into a multi-organ dysfunction syndrome, mediated by bacteria translation across dying gut wall
79
Q

What is chronic colonic ischaemia

A

Inflammation and injury of the large intestines due to inadequate blood supply

80
Q

What causes chronic colonic ischaemia

A 
Low BP 
Constriction of blood vessels
Blood clot 
Thrombosis
Emboli 
Decreased CO
Drugs (vasopressin)
Surgery 
Vasculitis (SLE)
Coagulation disorders
Idiopathic
81
Q

Risk factors for chronic colonic ischaemia

A

Contraceptive pill
Nicorandil drug
Thrombophilia
Vasculitis

82
Q

What arteries tend to be occluded in chronic colonic ischaemia

A
  1. Occlusion of branched superior mesenteric artery and inferior mesenteric artery
83
Q

Clinical presentation of chronic colonic ischaemia

A
  1. Sudden onset lower left side abdo pain
  2. Passage of red blood with NO diarrhoea
  3. Signs of shock
84
Q

What are the signs of shock

A
  1. Pale skin
    Weak rapid pusle
  2. Reduce Urine output
  3. Confusion
85
Q

Differential diagnosis of chronic colonic ischaemia

A

Other causes of acute colitis

86
Q

Diagnosis of chronic colonic ischaemia

A
  1. Urgent CT scan to exclude perforation
  2. Flexible sigmoidoscopy
  3. Colonoscopy and BIOPSY (GOLD STANDARD)
  4. Barium enema
87
Q

What would flexible sigmoidoscopy show in chronic colonic ischaemia

A
  1. Epithelial cell apoptosis
88
Q

When is colonoscopy and biopsy done for chronic colonic ischaemia

A
  1. After the patient has fully recovered to exclude stricture formation at the site of disease and confirm mucosal healing
89
Q

What is barium enemia in chronic colonic ischaemia

A

Thumb printing of submucosal swelling at splenic flexure

90
Q

How is chronic colonic ischaemia treated

A
  1. Fluid replacement
  2. Antibiotics
  3. Gangrenous ischaemic colitis
91
Q

Why are antibiotics given in chronic colonic ischaemia

A

To reduce infection risks due to translocation of bacteria across dying gut wall

92
Q

Clinical presentation of GANGRENOUS ischaemic colitis

A

Peritonitis

Hypovolaemic shock

93
Q

How is GANGRENOUS ischaemic colitis treated

A
  1. Prompt resus

2. Surgical resection of affected bowel and stoma formation

Year 2 (155 decks)

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