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Gastrointestinal > Lecture 15- Distal GI tract pathology > Flashcards

Lecture 15- Distal GI tract pathology Flashcards

1
Q

Definition of diarrhoea–

A

diarrhoea is a symptom and occurs in many conditions

  • Loose or watery stools
  • More than 3 times a day
  • Acute diarrhoea (less than 2 weeks)
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2
Q

pathophysiology of diarrhea

A
  • Unwanted substance in gut stimulates secretion and motility to get rid of it
  • Primarily down to epithelial function (secretion) rather than increased gut motility
    • End product has too much water in stool
  • Colon is overwhelmed and cannot absorbed the quantity of water it recovers from ileum
  • Normally 99% absorption of water from gut
    • Leaving only 100mls in stool
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3
Q

Fluid movement down GI tract- normal conditions

*

A
  • Water is not actively moved across gut (transcellular and paracellular)
  • Follows osmotic forces generated by movement of electrolytes/nutrients (sodium)
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4
Q

two broad categories of diarrhea

A

osmotic

secretory

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5
Q

Osmotic cause of D

A
  • Molecules in the gut of high osmotic pressure
  • E.g. malabsorption
  • Stool volume moderately increased
  • If you stop eating diarrhoea stops
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6
Q

Secretory cause of D

A
  • Toxin/bacteria
  • Water actively secreted into lumen of the gut
  • Stool volume large
  • Doesn’t respond to fasting
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7
Q

outline MOA of secretory diarrhea

A
  • Electrolyte transport is messed up
  • Too much secretion of ions (net secretion of bicarbonate or chloride)
  • Toxins/ virus can increase cAMP within cytosol of enterocyte increases activity of CFTR–> pumps out chloride ions –>sodium follows and then water
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8
Q

main causes of osmotic diarrhea

A

Osmotic causes

  • Gut lumen contains too much osmotic material caused by malabsorption
  • ingesting material that is poorly absorbed e.g. antacids
  • Inability to absorb nutrients e.g. lactose in lactase deficiency
  • Will stop if you stop consuming offending substance.
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9
Q
  • Other causes of osmotic diarrhea:
A
  • Too little absorption of sodium
    • Reduced surface area for absorption
    • Mucosal disease/ bowel resection (coeliac or crohns)
    • Reduced contact time (intestinal rush)
      • Diabetes
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10
Q

definition of constipation

A

Definition- suggestive of hard stools, difficulty passing stools or inability to pass stools

  • Straining during >25% of defecations
  • Lumpy or hard stools in 25% defecations
  • Feeling of incomplete evacuation in >25% of defecations
  • Having fewer than three unassisted bowel movement a week
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11
Q

Risk factors of constipation

A
  • Female: male 3:1
  • Opioid’s/ antidiarrheal medications
  • Low level of physical activity
  • Increasing age (but also common in children under 4 years)
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12
Q

types of constipation

A
  • normal transit constipation
  • slow colon transport

defaecation problems

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13
Q
  • Normal transit constipation
A

Related to other psychological stressors

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14
Q
  • Slow colon transport
A
  • Causes
    • Large colon (megacolon)
    • Fewer peristalitic movements (pacemaker cells of Cajal)
    • Systemic disorders (hypothyroidism, diabetes)
    • Nervous system disease (parkinsons, MS)
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15
Q

defaecation problems

A
    • Cannot coordinate muscle of defaecating/ disorders of the pelvic floor or anorectum
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16
Q

constipation treatments

A
  • Psychological support
  • Increased fluid intake
  • Increased activity
  • Increased dietary fibre (only useful for mild constipation)
  • Fibre medication
  • Laxative
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17
Q

laxative scan be

A

osmotic and stimulatory

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18
Q

osmotic laxative

A

ingesting molecule with osmotic effect - magnesium sulphate, disaccharides–> draw water into intestinal lumen

19
Q
  • Stimulatory laxative
A

(chloride channel activators)

20
Q

the appendix is an diverticulum off the cecum

A
  • Has a complete longitudinal layer of muscle (colon has incomplete bands called teniae coli)
21
Q

appendicitis

A

Inflammation of the appendix

22
Q

blood supply of appendix

A
  • Separate blood supply to the caecum coming up through a mesentery (mesoappendix) from ileocolic branch of SMA
23
Q
  • Location of appendix is important why
A
  • changes presentation of acute appendicitis
    • Retrocaecal
    • Pelvic
    • Sub- caecal
    • Para-ileal (pre or post)
24
Q

categories of appendicitis

A

Broad categories

  • Acute (mucosal oedema)
  • Gangrenous (transmural inflammation and necrosis)
  • Perforated –> peritonitis
25
Q

classic explanation of appendicitis

A
  • Blockage of appendiceal lumen creates pressure in the appendix –> faecal matter (faecalith), lymphoid hyperplasia due to a previous virus, foreign body
  • Causes venous pressure to rise (causing oedema in walls of appendix)
    • Make it harder for arterial blood supply
  • Ischaemia in walls of appendix
  • Bacterial invasion follows
26
Q
  • Alternative explanations of appendix
    *
A

A viral or bacterial infection causes mucosal changes that allow bacterial invasion of appendiceal wall

27
Q

classic symptoms of appendicitis

A
  • Classic
    • Poorly localised peri-umbilical pain
      • Pain referred to T9, T10
      • Following enlargement –> touches wall of abdo –>parietal peritoneum (RIF)
    • Anorexia
    • Nausea/vomiting
    • Low grade fever
    • 12-24h pain is felt more intensely in right iliac fossa
28
Q
  • If appendix is retro-caecal or pelvic in its position you may
    *
A
  • not get right iliac fossa pain
    • Parietal peritoneum in right iliac fossa does not come in contact with inflamed appendix
      • Supra-pubic pain, right sides rectal or vagina pain
29
Q

who are hard to diagnose appendicitis in

A
  • Children make It difficult to diagnose
    • History is difficult
    • Symptoms less specific
  • Preganancy
    • Anatomy altered
30
Q

signs of appendicits

A
  • Slight fever/ tachycaria
  • Generally lie quite still as peritoneum is inflamed  peritonitis
  • Localised right quadrant tenderness
  • Rebound tenderness in right iliac fossa appears to be relatively specific
31
Q

Rebound tenderness in right iliac fossa known as……

A

McBurnerys Point

more painful when moving hand away than pressing down

32
Q

Appendicitis- diagnosis/ treatment

A
  • Blood test
    • raised WBC
  • History or physical exam- if classic this might be enough
    • Especially if rebound tenderness
  • Pregnancy test/ urine dip
    • Rule out ectopic or UTI
  • In non-classical presentation (In the US)
    • CT scan will show distended appendix that doesn’t fill with contrast
33
Q

treatment of appendicitis

A
  • Open appendicectomy
  • Laparoscopic appendicectomy
34
Q

diverticulosis

A
  • Outpouchings in sigmoid colon
  • Outpouching in mucosa and submucosa herniate through the Musclaris layers
  • Occurs along where nutrient vessels (vasa recta) penetrate wall
35
Q
A
36
Q

symptoms of diverticulosis

A

asymptomatic

  • pain can be due to duverticula- not inflammation
37
Q

Acute diverticulitis

A
  • When diverticula become inflamed or perforated (+/- bleeding and abscess formation)
  • Occurs in 25% of people with diverticulosis
38
Q

pathophysiology of acute diverticulitis

A
  • Pathophysiology similar to appendicitis
    • Entrance to diverticula blocked by faces
    • Inflammation eventually allows bacterial invasion of the wall of the diverticula
    • Can lead to perforation
39
Q
  • Uncomplicated diverticulitis
    *
A

Inflammation and small abscess confined to colonic wall

40
Q
  • Complicated diverticulitis
    *
A

Larger abscess, fistula and perforation

41
Q
A
42
Q

Symptoms of acute diverticulitis

A
  • Abdominal pain at site of inflame
  • Fever
  • Bloating
  • Constipation
43
Q

diagnosis of acute diverticulitis

A
  • Blood tests
    • Blood tests
    • USSS
  • CT scan – extra mural problems
  • Colonoscopy if large haematochezia  dont want to perforate
    • Elective colonoscopy- after things have settled- to determine cause of symptoms if unclear
44
Q
  • Treatment of diverticulitis
A
  • Antibiotics, fluid rescuscitation and analgesia
    • Uncomplicated diverticulitis= analgia and oral antibiotics
  • Surgery if perforation or large abscesses need to be drain
    • Partial colectomy required if other treatment fail

Gastrointestinal (35 decks)

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