Lecture 15- Distal GI tract pathology Flashcards
(44 cards)
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)
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
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)
4
Q
two broad categories of diarrhea
A
osmotic
secretory
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
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
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
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.
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
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
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)
12
Q
types of constipation
A
- normal transit constipation
- slow colon transport
defaecation problems
13
Q
- Normal transit constipation
A
Related to other psychological stressors
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)
15
Q
defaecation problems
A
- Cannot coordinate muscle of defaecating/ disorders of the pelvic floor or anorectum
16
Q
constipation treatments
A
- Psychological support
- Increased fluid intake
- Increased activity
- Increased dietary fibre (only useful for mild constipation)
- Fibre medication
- Laxative
17
Q
laxative scan be
A
osmotic and stimulatory
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
classic explanation of appendicitis
* 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
* Alternative explanations of appendix
*
A viral or bacterial infection causes mucosal changes that allow bacterial invasion of appendiceal wall
27
classic symptoms of appendicitis
* 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
* If appendix is retro-caecal or pelvic in its position you may
*
* 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
who are hard to diagnose appendicitis in
* Children make It difficult to diagnose
* History is difficult
* Symptoms less specific
* Preganancy
* Anatomy altered
30
signs of appendicits
* 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
Rebound tenderness in right iliac fossa known as......
McBurnerys Point
more painful when moving hand away than pressing down
32
**Appendicitis- diagnosis/ treatment**
* 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
treatment of appendicitis
* Open appendicectomy
* Laparoscopic appendicectomy
34
diverticulosis
* Outpouchings in sigmoid colon
* Outpouching in mucosa and submucosa herniate through the Musclaris layers
* Occurs along where nutrient vessels (vasa recta) penetrate wall
35
36
symptoms of diverticulosis
asymptomatic
- pain can be due to duverticula- not inflammation
37
**Acute diverticulitis**
* When diverticula become inflamed or perforated (+/- bleeding and abscess formation)
* Occurs in 25% of people with diverticulosis
38
pathophysiology of acute diverticulitis
* 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
* Uncomplicated diverticulitis
*
Inflammation and small abscess confined to colonic wall
40
* Complicated diverticulitis
*
Larger abscess, fistula and perforation
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42
**Symptoms of acute diverticulitis**
* Abdominal pain at site of inflame
* Fever
* Bloating
* Constipation
43
diagnosis of acute diverticulitis
* **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
* Treatment of diverticulitis
* 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
