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GI > Lecture 15- Distal GI tract pathology > Flashcards

Lecture 15- Distal GI tract pathology Flashcards

1
Q

Diarrhoea

A

Loose or watery stool
Occurs 3 + times a day

Acute - for less than 2 weeks

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2
Q

Causes of diarrhoea

A

Excessive secretion of ions by e.g. cholera toxin

Inadequate absorption of sodium:

  • reduced SA
  • Bowel resection
  • Mucosal disease - Coeliac’s or Crohn’s
  • reduced contact time - diabetes and IBS

Malabsorption

  • indigested material that is poorly absorbed
  • antacids - magnesium sulphate
  • Inability to absorb nutrients - lactose intolerance
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3
Q

Constipation

A

Difficulty or inability to pass stools

In more than 25% of defaecations:

  • Straining
  • Hard or lumpy stool
  • Feeling of incomplete evacuation
  • Feeling of blockage
  • Fewer than 3 unassisted bowel movements per week
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4
Q

RF for constipation

A 
Female
Medication - codine
Old age 
Low physical activity 
Drinking less water
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5
Q

Pathophysiology of constipation

A

Slow colonic transport

  • megacolon
  • Decreased peristalsis
  • Fewer intestinal pacemaker cells present
  • Hypothyroidism
  • diabetes
  • Parkinsons and MS
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6
Q

Movements in colon

A

Shuttling
Peristalsis
Gastrocolic movement -mass movement

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7
Q

Treatments of constipation

A 
Psychological 
Increased fluid intake 
Increased activity 
Laxatives - magnesium sulphate , dissacharides, chloride channel activators and stool softners
Increased fibre intake 
Fibre medication
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8
Q

Appendix

A

Diverticulum of caecum
Complete longitudinal layer of muscle
Seperate blood supply from caecum - ileocolic artery from mesentery

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9
Q

Appendicitis pain

A

Midgut structure - peri-umbilical pain

If touches parietal peritoneum - right iliac fossa pain

If long and runs in pelvis - pelvic and rectal pain

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10
Q

Categories of appendicitis

A

Acute - mucosal oedema
Gangrenous - transmural and necrosed
Perforated - peritonitis

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11
Q

Causes of appendicitis

A
  1. Blockage in lumen due to faecolith, lymphoid hyperplasia or foreign body
  2. Increase in pressure in appendix
  3. Increased venous pressure causing oedema
  4. Decreased arterial supply causes ischaemia and bacterial invasion due to stasis

Also caused by viral or bacterial infection - mucosal changes for bacterial invasion

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12
Q

Symptoms of appendicitis

A 
Poorly localised peri-umbilical pain
Nausea and vomiting
Anorexia
Low grade fever 
If persists more than 12 hours - RLQ (iliac fossa) pain
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13
Q

Sign of appencitis

A

Rebound tenderness:
Palpation - pain felt when let go as there is a sharp movement of the peritoneum

McBurney’s point - 2/3rds of the way from umbilicus to ASIS

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14
Q

Diagnosis of appendicitis

A

Blood test - WBC

History and examination for rebound tendernous

Pregnancy test

CT - distended appendix doesn’t fill with contrast

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15
Q

Treatment of appendicitis

A

Open or laproscopic appendicectomy

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16
Q

Diverticulum

A

Outpouching of mucosa and submucosa which herniates through the muscularis layer

Where nutrient vessels (vasa recta) penetrate the bowel wall as weakest

Asymptomatic
Occurs in colon - 85% sigmoid colon

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17
Q

Cause of diverticulosis

A

Increased intraluminal pressure due to low fibre diet

18
Q

Acute diverticulitis

A

Diverticulum becomes inflamed or perforated +/- bleeding and abscess formation

25% of diverticulosis:

  • Entrance of diverticulum is blocked by faecolith
  • Inflammation causes bacterial invasion of the diverticula wall
  • Can be perforated
19
Q

Uncomplicated diverticulitis

A

Inflammation and abscesses confined to colonic wall

20
Q

Complicated diverticulitis

A

Larger abscesses
Fistulas
Perforation

21
Q

Sign and symptoms of acute diverticulitis

A 
Abdominal pain normally LLQ
Constipation - inflammation blocks lumen
Fever
Bloating 
Haematochezia - blood in stool

Signs:
Abdominal tenderness
Decreased bowel sounds - decreased bowel movements
Distention
Signs of peritonitis if perforated e.g. nausea and vomiting

22
Q

Acute diverticulitis investigations

A

Bloods - raised WBCs

Pregnancy test

Colonoscopy - if haematocheizia but may cause perforation

USS

CT

23
Q

Treatment of diverticulitis

A

Antibiotics
Fluid resuscitation - saline
Analgesia

Surgery if perforated
Large abscesses are drained

24
Q

Structure of rectum

A

Outer continuous longitudinal muscle

Curved shape anterior to sacrum

Partly intraperitoneal and retroperitoneal

When distended, triggers urge to defecate as temporary store of faeces before defaecation

25
Q

Blood supply

A

Superior rectal artery - IMA ( after pelvic brim)
Middle rectal artery - internal iliac
Inferior rectal artery - pudendal artery

Venous drainage:
- Portal drainage through superior rectal vein

  • Systemic drainage - internal iliac vein
26
Q

Anal canal

A

Narrow continuation of the rectum from the anal sphincter

The rectum points anteriorly but the puborectalis muscle acts like a sling causing the anal canal to point posteriorly

27
Q

Factors affecting continence

A 
Distensible rectum
Anal canal angle via puborectalis
Firm stool 
Anal cushions
Normal anal sphincter
28
Q

Internal involuntary sphincter

A

Thickening of circular smooth muscle
Under autonomic control

Contributes 80% to resting anal pressure

29
Q

External anal sphincter

A

Striated muscle

The deep section mixes with levator ani muscles and joins with the puborectalis muscle to form a sling

Also has superficial and subcutaneous section

Innervated by the pudendal nerve

20% anal pressure at rest

30
Q

Dentate line

A

Junction between the hindgut and proctodaeum

31
Q

Above dentate line

A

Visceral receptors and columnar epithelium

  • pain less felt
32
Q

Below dentate line

A

Somatic pain receptors
Stratified squamous epithelium

  • Pathology is painful
33
Q

Haemorroid tissue

A

Anal cushions - normal swellings of veins and arteries

  • Complex venous plexus
  • role in anal continence
34
Q

Haemorrhoids

A

Symptomatic anal cushions

  • internal and external haemorrhoids
35
Q

Internal haemorroids

A

Above dentate line - painless
Loss of connective tissue support
Enlarge and prolapse into the anal canal
Bleeding - pruritis (bright red)

36
Q

Treatment of internal haemorrhoids

A 
Hydration
High fibre diet
Avoid straining
Surgery if severe
Rubber band ligation
37
Q

External haemorrhoids

A

Below dentate line - painful
Swelling of the anal cushions that may thrombose

Surgery required

38
Q

Anal fissure

A

Linear tear in anoderm
Hematochezia
pain when defaecating

Caused by:

  • Increased internal anal sphincter tone
  • Decreased blood flow to anal mucosa

Treatment:

  • Rehydration
  • High fibre diet
  • Medication to relax sphincter
  • Warm baths
  • Analgesia
39
Q

Melaena

A

Black tarry stool
Offensive smell
Hb altered by digestive enzymes in the gut

Due to:
Peptic ulcers
Variceal bleeds
Oesophageal or gastric cancer
Upper GI malignancy
40
Q

Meckel’s diverticulum

A

Congenital outpouching of the lower small intestines

Remnant of the umbilical cord

GI (18 decks)

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