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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
What carcinoma causes peritoneal tumours to form
Ovarian carcinomas
26
What are signs of any bowel obstructions
Tinkling bowel sounds Tympanic percussion
27
What usually causes SMALL BOWEL obstruction
A previous surgery OR Crohn's disease
28
Main mechanisms that cause SBO
1. ADHESIONS 2. Hernias Any mechanical obstructions
29
What surgeries in particular will cause adhesions and thus small bowel obstructions
Pelvic, gyro and colorectal surgery
30
Long-term effect of hernias on the GI tract
STRANGULATION
31
How does obstruction effect the small bowel
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
32
What happens if small bowel disease is left untreated
1. Ischaemia 2. Necrosis 3. Perforation
33
Clinical presentation of SBO
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
34
Four diagnostics for SBO
1. Abdo X-ray 2. Examination of hernia orifices and rectum 3. FBC 5. GOLD STANDARD - CT
35
What does a CT show in SBO
Localise lesions
36
Role of AXR in SBO
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
37
How is SBo treated
1. Fluid resus 2. Bowel decompression 3. Analgesia and antiemetic 4. Antibiotics 5. Surgery (remove obstruction via laparotomy)
38
What are antiemetics
Treat vomiting and nausea
39
How long does it take for LBOs to present
5 days until symptoms occur as it has a larger lumen
40
Why does it take a while for symptoms to occur and why is it rare for LBOs to occur
1. Larger lumen | 2. Circular and longitudinal muscles all large bowel to distend much greater
41
What usually causes LBO
Colorectal malignancies rarely volvulus
42
What part of the colon dilates in LBO
The colon proximal to obstruction dilates
43
How does this effect blood flow and colonic pressure in LBO (dilatation)
Increases colonic pressure Decreased mesenteric blood flow = mucosal oedema
44
What is mucosal oedema
Transudation of fluid and electrolytes from the lumen
45
How can dilatation of the LBO effect arterial blood supply
Mucosal oedema caused can ischaem the arteries and cause mucosal ulceration
46
Result on mucosal ulceration on GI
Full thickness necrosis and perforation
47
How does sepsis effect the GI tract i LBO
Bacterial translocation
48
What happens in a colonic volvulus
1. There is axis rotation based of mesentery and a 360 degree twist resulting in a closed loop obstruction
49
How does a colonic volvus effect pressure/blood flow and contents of the GI tract in LBO
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
CLinical presenttation of LBO
1. Abdo pain 2. Abdo distention 3. Bowel sounds normal than increased then quiet later 3. Palpable mass 4. Late vomiting (faecal-like) 5. Constipation 6. Fulllness/bloating/Nausea
51
How to diagnose LBO
1. Digital rectal exam 2. FBCs 3. AXR 4. CT
52
What do we look for in a digital rectal exam for LBO
1. Empty rectum 2. Hard stools 3. Blood
53
What would we look for in FBCs for LBO
Low Hb (Cause bloody stools)
54
What would AXR show for LBO
1. Peripheral gas shadows proximal to the blockage (in caecum not rectum) UNLESS PR examination is done 2. Distended caecum and ascending colon
55
How is LBO treated
1. Aggressive fluid resus 2. Bowel decompression 3. Analgesia + antiemetic 4. Antibiotics 5. Surgery (removes obstruction done by laparotomy (open surgery)
56
How are obstructions in the LBO due to malignancy treated
1. Colorectal stents followed by elective surgery
57
What is pseudo-obstruction
Mimics obstruction but with no mechanical cause
58
What usually causes pseudo-obstruction
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
Clinical presentation of pseudo-obstruction
Progressive abdo distention and pain
60
How is pseudo-obstruction diagnosed
Gas-filled large bowel
61
How is pseudo-obstruction treated
Treat underlying problem IV NEOSTIGMINE (
62
What three types of bowel ischaemia are there
1. Acute mesenteric ischaemia 2. Chronic mesenteric ischaemia (intestinal angina) 3. Ischaemic colitis (Chronic colonic ischaemia)
63
What blood supplies the colon
1. Inferior superior mesenteric arteries
64
What are watershed areas
Splenic flexure | Caecum
65
What does AF with abdo pain indicate (conditions wise)
Mesenteric Ischaemia
66
What part of the GI tract is effected by acute mesenteric ischaemia
Small bowel
67
What is the most common cause of acute mesenteric ischaemia
Superior mesenteric artery thrombosis
68
How does AF cause acute mesenteric ischaemia
Superior mesenteric artery embolism
69
In which patients is mesentery vein thrombosis a cause for acute mesenteric ischaemia
Younger patients
70
What other factor causes acute mesenteric ischaemia
Non-occlusive diseases
71
Clinical presentation of acute mesenteric ischaemia
1. Acute severe abdo pain (constant, central at right iliac fossa) 2. No abdo signs 3. Rapid hypovolaemia resulting in shock
72
How is acute mesenteric ischaemia diagnosed
1. Bloods 2. AXR 3. Laparotomy 4. CT/MRI angiography
73
What would we see in blood tests for acute mesenteric ischaemia
Raised Hb due to plasma loss Raised WBC Persistent metabolic ACIDOSIS
74
What would we see in AXR for acute mesenteric ischaemia
1. Used to rule out other pathologies and gads-less abdomen
75
What is a laparotomy
1. Surgical procedure -> cut into abdo wall -> access abdo cavity
76
Why is a laparotomy used for acute mesenteric ischaemia
To make diagnosis See necrotic bowel
77
How is acute mesenteric ischaemia treated
1. Fluid resus 2. Antibiotics (IV GENTAMICIN + METRONIDAZOLE) 3. IV HEPARIN to reduce clotting 4. Surgery to remove dead bowel
78
Complications of treating acute mesenteric ischaemia
1. Septic peritonitis 2. Systemic inflammatory response syndrome progressing into a multi-organ dysfunction syndrome, mediated by bacteria translation across dying gut wall
79
What is chronic colonic ischaemia
Inflammation and injury of the large intestines due to inadequate blood supply
80
What causes chronic colonic ischaemia
``` Low BP Constriction of blood vessels Blood clot Thrombosis Emboli Decreased CO Drugs (vasopressin) Surgery Vasculitis (SLE) Coagulation disorders Idiopathic ```
81
Risk factors for chronic colonic ischaemia
Contraceptive pill Nicorandil drug Thrombophilia Vasculitis
82
What arteries tend to be occluded in chronic colonic ischaemia
1. Occlusion of branched superior mesenteric artery and inferior mesenteric artery
83
Clinical presentation of chronic colonic ischaemia
1. Sudden onset lower left side abdo pain 2. Passage of red blood with NO diarrhoea 3. Signs of shock
84
What are the signs of shock
1. Pale skin Weak rapid pusle 3. Reduce Urine output 4. Confusion
85
Differential diagnosis of chronic colonic ischaemia
Other causes of acute colitis
86
Diagnosis of chronic colonic ischaemia
1. Urgent CT scan to exclude perforation 2. Flexible sigmoidoscopy 3. Colonoscopy and BIOPSY (GOLD STANDARD) 4. Barium enema
87
What would flexible sigmoidoscopy show in chronic colonic ischaemia
1. Epithelial cell apoptosis
88
When is colonoscopy and biopsy done for chronic colonic ischaemia
1. After the patient has fully recovered to exclude stricture formation at the site of disease and confirm mucosal healing
89
What is barium enemia in chronic colonic ischaemia
Thumb printing of submucosal swelling at splenic flexure
90
How is chronic colonic ischaemia treated
1. Fluid replacement 2. Antibiotics 3. Gangrenous ischaemic colitis
91
Why are antibiotics given in chronic colonic ischaemia
To reduce infection risks due to translocation of bacteria across dying gut wall
92
Clinical presentation of GANGRENOUS ischaemic colitis
Peritonitis | Hypovolaemic shock
93
How is GANGRENOUS ischaemic colitis treated
1. Prompt resus | 2. Surgical resection of affected bowel and stoma formation

Year 2 (155 decks)

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