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ESA 3 - Gastrointestinal System > Distal GI Tract Pathology > Flashcards

Distal GI Tract Pathology Flashcards

1
Q

What is the definition of diarrhoea?

A

A symptom that occurs in many conditions

Loose watery stools
More than 3 times a day

Acute diarrhoea -less than 2 weeks

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2
Q

What is the pathophysiology of diarrhoea?

A

Unwanted substance in gut stimulates secretion and motility to get rid of it.

Primarily down to epithelia function (secretion) rather than increased gut motility (although this does occur)

Colon is overwhelmed and cannot absorb the quantity of water it receives from the ileum.

There is normally 99% absorption of water from the gut, leaving only 100mls in stools / day

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3
Q

How dos fluid normally move down GI tract?

A

Water is not actively moved across the gut but follows osmotic forces generated by the movement of electrolytes / nutrients

Normally 10/12L out of stomach and only poo out 100ml - lots of absorption

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4
Q

What are the broad causes of diarrhoea?

A

Secretory - electrolyte transport is messed up
-Too much secretion of ions (net secretion of chloride or bicarbonate)
-This will mess up the messenger systems that control ion transport. e.g. caused my infectious toxins.
Too little absorption of Na - reduce SA for absorption,
-Mucosal disease / bowel resection (Coeliac or IBD)
-Reduced contact time (diabetes / IBS)

Osmotic - the gut lumen contains too much osmotic material (malabsorption)

  • Ingesting material that is poorly absorbed
  • Inability to absorb nutrients (lactase deficiency)

-Osmotic diarrhoea will stop if you stop ingesting the substance; in secretory, diarrhoea will carry on until underlying pathology has settled down.

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5
Q

What is constipation?

A

Hard stools, difficulty passing stools or inability to pass stools.

In over 25% of bowel movements:

  • Straining
  • Feeling of incomplete evacuation
  • Obstruction or blockage to defecation

Also fewer than 3 unassisted bowel movements in a week.

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6
Q

What are the risk factors for constipation?

A 
Females:Males
Certain medications
Low levels of physical activity (immobile)
Increasing age
Children under 4
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7
Q

What is the pathophysiology of constipation?

A

3 different ways:

Normal transit constipation
-Psychological stressors

Slow colonic transport

  • Large colon (megacolon)
  • Fewer peristaltic movements and shorter ones
  • Fewer intestinal pacemaker cells present
  • Systemic disorders (hypothyroidism, diabetes)
  • Nervous system disease (Parkinson’s, MS)

Defaecation problems

  • Cannot coordinate muscles of defaecation
  • Disorders of the pelvic floor or anorectum
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8
Q

What are the treatments for constipation?

A 
Psychological support
Increased fluid intake 
Increased activity
Increased dietary fibres
Fibres medication 
Laxatives -Osmotic/Stimulatory/Stool softeners
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9
Q

What is appendicitis?

A

Swelling of appendix

Periumbilical pain their right iliac fossa.
BUT, this pattern of pain depends on where the appendix it.

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10
Q

What are the broad categories of appendicitis?

A

Acute (mucosal oedema)

Gangrenous (transmural inflammation and necrosis)

Perforated

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11
Q

What are the causes of appendicitis?

A

Classical- blockage (faecolith, lymphoid hyperplasia, foreign body) of appendiceacal lumen created higher pressure in the appendix
This causes venous pressure to rise, causing oedema in the walls of the appendix.
This makes it harder for arterial blood to supply the appendix resulting in ischaemia in the walls. A bacterial infection will then follow.

Alternatively:
A viral bacterial infection causes mucosal changes that allow bacterial invasion of appendiceal walls.

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12
Q

What are the symptoms of appendicitis?

A

Classical presentation (<60% of cases)

  • Poorly localised peri-umbilical pain
  • Nausea / vomiting
  • Low grade fever
  • After 12-14 hours, intense pain in RIF
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13
Q

What are the signs of appendicitis?

A 
ill
Lie still 
Slight fever / tachycardia 
Localised right quadrant tenderness 
Rebound tenderness in RIF appears relatively specific.
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14
Q

How do you diagnose appendicitis?

A

Blood test - raised WBC but non-specific

History / physical exam - if classical, could be enough, especially if rebound tenderness in RIF

Pregnancy test / urine dip to rule out UTI (no ectopics as can be similar pain)

CT - distended appendix that doesn’t fill with contract.

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15
Q

How do you treat appendicitis?

A

Open appendectomy

Lacroscopic appendicectomy

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16
Q

What is diverticulosis?

A

Multiple pouches (diverticula) in the colon (85% in sigmoid) that are not inflamed.

These are outpockets of the colonic mucosa and submucosa through weaknesses of muscularis layers in the colon wall.

They typically cause no symptoms and occur where nutrient vessels (vasa recta) penetrate the bowel wall.

The are thought to be caused by increased intra-luminal pressure (low fibres diet)

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17
Q

What is acute diverticulitis?

A

This is when the diverticula becomes inflamed or perforate (+/- bleeding and abscess formation)

Occurs in up to 25% of people with diverticulosis

18
Q

What are the symptoms of acute diverticulitis?

A

Abdominal pain at the site of the inflammation - usually left lower quadrant (most in sigmoid colon)

Fever

Bloating

Constipation (inflammation can block colonic lumen)

Haematochezia (fresh red blood in stools)

19
Q

What are the signs of diverticulitis?

A

Localised abdominal tenderness

Distention

Reduced bowel sounds

Signs of peritonitis (following perforation)

20
Q

How do you diagnose diverticulitis?

A

Blood test - raised WBC

Pregnancy test - rule out ectopic

USS

CT

Colonoscopy - if large haematochezia

Elective colonoscopy (after symptoms have settled) to determine causes of symptoms if unclear.

21
Q

How do you treat acute diverticulitis?

A

Antibiotics, fluid resuscitation, analgesia.

Surgery if perforation or large abscess need to be drained..

22
Q

Describe the rectum

A

12-15cm long passes through the pelvic floor.

Has a continuous band of outer longitudinal muscles

Curved shape anterior to sacrum

Parts of it are covered in peritoneum and parts are extra-peritoneal.

Temporary storage of fecaes prior to defaecation - stretching of rectum stimulates urge to deficaete.

23
Q

Describe the blood supply to rectum and anal canal

A

Superior rectal artery - continuation of inferior mesenteric.

Middle rectal artery - continuation of internal iliac.

Inferior rectal artery - continuation of prudential artery

24
Q

Describe the venous drainage of the rectum and anal canal

A

Portal drainage through the superior rectal vein

Systemic drainage through the internal iliac vein -there is potential for porto-systemic anastomosis here.

25
Q

Describe the anatomy of the anal canal

A

The anal canal is a narrowed portion of the GI tract that continues on from the rectum.

26
Q

What is the start of the anal canal?

A

It starts from the proximal border of the anal sphincter complex.

The rectum points anteriorly whereas the anal canal points posteriorly. This change in direction occur because of the pubo-rectalis sling.

27
Q

What factors are required for continence

A 
Dstensible rectum
Firm, bulky faeces 
Normal anorectal angle 
Anal cushions 
Normal anal sphincters
28
Q

What is the anal sphincter complex?

A

Made from both the internal and external sphincter.

Internal, involuntary sphincter:

  • Thickening of circular smooth muscle
  • Under autonomic control (80% of resting anal pressure.

External anal sphincter:

  • Striated muscle
  • Deep section is in the upper anal canal. It mixes with fibres from levator ani and joins with pubo-rectalis to form a sling.
  • Superficial and subcutaneous sections
  • Nerve supply from pudendal nerve
  • 20% of resting pressure.
29
Q

Describe the process of defecation

A

Mass movements lead to defecation reflex

This then leads to increased pressure in rectum and you can either delay or defecate

30
Q

What is the dentate line and what does this separate?

A

The dentate line is the junction between the hindgut and the proctodaeum (ectoderm)

Above: Visceral pain receptors, columnar epithelium

Below: somatic pain receptors, stratified squamous epithelia

31
Q

What are anal cushions?

A

They are a complex venous plexus that is divided into three areas called anal cushions.

These play a role in anal continence -inflate and deflate

There are connections between the veins and some arteries

They are present from birth and a normal finding

32
Q

What are internal haemorrhoids?

A

Symptomatic anal cushions (haemorrhoids)

  • Loss of connective tissue support
  • Above dentate line
  • Relatively painless
  • Enlarge and prolapse through anal canal
  • Bleed bright red / pruritus

Treatment:

  • Increased hydration / high fibre diet
  • Avoid straining
  • Rubber band ligation
  • Surgery
33
Q

What are external haemorrhoids?

A

Below dentate line so painful.
Swelling of anal cushions which may then thrombus
Surgery

34
Q

What are anal fissures?

A

Linear tear in the anoderm (usually posterior midline)

  • Passing of hard stools (Diarrhoea?)
  • Haematochezia
35
Q

What are the causes of anal fissures?

A

High anal sphincter tone

Reduced blood flow to anal mucosa

36
Q

What are the treatments for anal fissures?

A

Hydration, dietary fibre, analgesia

Warm baths

Medication trying to relax anal sphincter

37
Q

What are some common causes of haematochezia?

A

Diverticulitis

Angiodysplasia (small vascular malformation in the bowel)

Colitis (IBD, infective)

Colorectal cancer

Anorectal disease (haemorrhoids, anal fissure)

Upper GI bleeding - large bleed with fast transit

38
Q

What is melaena?

A

Black tarry stools that are often foul smelling.

It occurs due to Hb being altered by digestive enzymes and gut bacteria.

39
Q

What are some common causes of melaena?

A

Upper GI bleeding:

  • Peptic ulcer disease
  • Variceal bleeds
  • Upper GI malignancy
  • Oesophageal/ gastric cancers

Uncommon causes:

  • Gastritis
  • Meckel’s diverticulum
  • Iron supplements.
40
Q

In appendicitis, when would you not get paining the right iliac fossa?

A

If the appendix is retro-caecal or pelvic as the parietal peritoneum does not come into contact with the inflamed appendix. Instead, suprapubic or right sided rectal or vaginal pain.

Also possible in children as symptoms are much more non-specific or in pregnancy as the anatomy is altered.

41
Q

Describe the pathophysiology of diverticulitis

A

Similar to appendicitis.

  • Entrance to diverticula is blocked by faeces
  • Inflammation eventually allows bacterial invasion of the wall of the diverticula
  • Can lead to perforation.

It is uncomplicated if the inflammation and small abscess is confined to the colonic wall and complicated if the abscess is larger, there are fistulas or it has perforated.

ESA 3 - Gastrointestinal System (18 decks)

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