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Gastrointestinal > Distal GI Tract Pathology > Flashcards

Distal GI Tract Pathology Flashcards

1
Q

Define diarrhoea.

A

Loose or watery stools, more than 3 times a day.

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2
Q

What is acute diarrhoea?

A

Diarrhoea for less than 2 weeks.

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3
Q

What is the pathophysiology of diarrhoea?

A

Unwanted substance in gut stimulates secretion and and motility to get rid of it, by epithelial function more than increased gut motility.
The colon is overwhelmed and cannot absorb the quantity of water it receives from ileum.

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4
Q

What are the 2 broad causes of diarrhoea?

A
  1. Osmotic,

2. Secretory.

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5
Q

What secretory problems can cause diarrhoea?

A
  1. Too much secretion of ions (net secretion of chloride or bicarbonate), affecting the messenger systems that control ion transport.
  2. Too little absorption of sodium: reduced SA for absorption, mucosal disease and reduced contact time like with diabetes.
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6
Q

What osmotic problems can cause diarrhoea?

A

Gut lumen contains too much osmotic material like ingesting material that is poorly absorbed (antacids-magnesium sulphate), inability to absorb nutrients. Stops when the offending substance is stopped consuming.

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7
Q

What is constipation?

A

Hard stools, difficulty passing stools or inability to pass stools.
Straining during more than 1/4 of defecations, feeling incomplete on defecation, obstruction or having fewer than 3 unassisted bowel movements in a week.

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8
Q

What are the risk factors of constipation?

A
  1. Female,
  2. Certain medications.
  3. Low level of physical activity.
  4. Increasing age (or younger than 4).
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9
Q

What is the pathophysiology of constipation?

A
  1. Normal transit constipation (psychological stressors).
  2. Slow colonic transport: large colon, fewer peristaltic movements, fewer intestinal pacemaker cells (intestinal cells of Cajal), systemic disorders, nervous system disease.
  3. Defaecation problems: can’t coordinate muscles.
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10
Q

How do you treat constipation?

A
  1. Psychological support.
  2. Increased fluid intake.
  3. Increased activity.
  4. Increased dietary fibre.
  5. Fibre medication.
  6. Laxatives.
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11
Q

What is the appendix?

A

A diverticulum of the caecum.
Has a complete longitudinal layer of muscle.
Separate blood supply to caecum coming up through a mesentery (mesoappendix) from the ileocolic branch of the SMA.

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12
Q

What are the different locations the appendix can be found?

A
  1. Retro-caecal.
  2. Pelvic.
  3. Sub-caecal.
  4. Para-ileal.
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13
Q

What are the different types of appendicitis?

A
  1. Acute (mucosal oedema).
  2. Gangrenous (transmural inflammation and necrosis).
  3. Perforated.
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14
Q

What are the causes of the appendicitis?

A
  1. Blockage of appendiceal lumen, creates a higher pressure in the appendix (due to lymphoid hyperplasia, foreign body or faecolith), causes rise in venous pressure, making arterial blood harder to get to, this causes ischaemia and subsequent bacterial infection.
  2. Viral or bacterial infection causes mucosal changes that allow bacterial invasion of appendiceal walls.
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15
Q

What are the symptoms of appendicitis?

A
  1. Poorly localised peri-umbilical pain.
  2. Anorexia.
  3. Nausea/vomiting.
  4. Low grade fever.
  5. After 12-24hours pain it moves to right iliac fossa and is more intense.
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16
Q

Describe variations in symptoms of appendicitis.

A

If retro-caecal/pelvic in its position you may not get right iliac fossa pain. Parietal peritoneum in right iliac fossa in right iliac fossa does not come in contact with inflamed appendix.
Children hard to diagnose and it is different in pregnancy.

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17
Q

What are the signs of appendicitis?

A
  1. Patients appear slightly ill.
  2. Slight fever.
  3. Tachycardia.
  4. Lie quite still as peritoneum is inflamed.
  5. Localised. right quadrant tenderness.
  6. Rebound tenderness in right iliac fossa.
  7. Pain in McBrunery’s point.
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18
Q

How do you diagnose appendicitis?

A
  1. Blood tests- raised WBC- non specific.
  2. History/physical examination- if classic symptoms it’ll be enough.
  3. Rebound tenderness in RIF.
  4. Pregnancy test.
  5. Non-classical: do a CT scan.
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19
Q

How do you treat appendicitis?

A
  1. Open appendectomy.

2. Laparoscopic appendicectomy.

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20
Q

What is diverticulosis?

A

Diverticulosis is asymptomatic, occurring mainly in the sigmoid colon. There is outpouches of mucosa and submucosa which herniate through the muscular layers. Occurs along where a nutrient vessel penetrate the bowel wall, due to increased intra-luminal pressure like due to a low fibre diet.

21
Q

What is diverticular disease?

A

Pain from diverticula but with no inflammation/infection.

22
Q

What is acute diverticulitis?

A

Is when diverticula becomes inflamed or perforate (with bleeding and abscess formation potentially). It occurs in 25% of people with diverticulosis.
It occurs when the entrance to the diverticula is blocked by faeces, inflammation eventually allows bacterial invasion of the wall of the diverticulitis and can lead to perforation.

23
Q

What are the 2 types of diverticulitis?

A
  1. Uncomplicated diverticulitis: inflammation and small abscesses confined to colonic wall.
  2. Complicated diverticulitis: larger abscesses, fistula, perforation.
24
Q

What are the symptoms of diverticulitis?

A
  1. Abdominal pain at the site of the inflammation (left lower quadrant in sigmoid colon).
  2. Fever (inflammation and infection).
  3. Bloating.
  4. Constipation.
  5. Haematochezia (large amount of blood loss).
25
Q

What are the signs of diverticulitis?

A
  1. Localised abdominal tenderness.
  2. Distension.
  3. Reduced bowel sounds.
  4. Signs of peritonitis following perforation.
26
Q

How do you diagnose acute diverticulitis?

A
  1. Blood tests-> raised WBC, pregnancy test.
  2. CT scan.
  3. Colonoscopy if large haematochezia.
  4. Elective colonoscopy after symptoms have settled.
27
Q

What is the treatment of acute diverticulitis?

A
  1. Antibiotics, fluid resuscitation and analgesia.

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

28
Q

Describe the rectum anatomically.

A

The rectum is 12-15cm long and passes through the pelvic floor.
The rectum has a continuous band of outer longitudinal muscles, curved shape anterior to sacrum. Parts of it are covered in peritoneum.
It provides temporary storage of faeces prior to defaecation.

29
Q

Describe the blood supply to the rectum.

A

Superior rectal artery continuation of the inferior mesenteric artery.
Middle rectal artery- internal iliac artery.
Inferior rectal artery- pudendal artery.

30
Q

Describe the venous supply to the rectum.

A

Portal drainage through the superior rectal vein.

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

31
Q

Describe the anal canal.

A

Narrowed part of the GI tract that continues on from the rectum.
The rectum points anteriorly and the. pubo-rectal sling changes the direction of the anatomy for the anal canal to point posteriorly,

32
Q

What factors are required for continence?

A
  1. Distensible rectum.
  2. Firm bulky faeces.
  3. Normal anorectal angle.
  4. Anal cushions.
  5. Normal anal sphincters.
33
Q

Describe the internal involuntary sphincter.

A

Thickening of circular smooth muscle that is under autonomic control.

34
Q

Describe the external anal sphincter.

A

Striated muscle found in the upper anal canal. It mixes with fibres from the levator ani and joins the pubo-rectalis to form a sling.
It is supplied by the pudendal nerve.

35
Q

What is the process of defaecation?

A
  1. There is a mass movement.
  2. Defecation reflex due to distension of the rectum, this causes contraction of the colon, relaxation of the internal anal sphincter and contraction of the external anal sphincter.
  3. There is increased pressure in the rectum that can either lead to delay or defacation
36
Q

What is the pectinate line?

A

The junction of hindgut and proctodaeum (ectoderm).

37
Q

Describe the area above the pectinate line.

A

There are visceral pain receptors and it is covered in visceral pain receptors.

38
Q

Describe the area below the pectinate line.

A

There are somatic pain receptors and the epithelium is stratified squamous.

39
Q

What are anal cushions?

A

A venous plexus, divided into 3 areas. They are important for continence. There are some connections between the veins and arteries.
They are present from birth and a normal finding.

40
Q

What are internal haemorrhoids?

A

Symptomatic anal cushions occurring due to loss of connective tissue support above the pectinate line. Thus they are relatively painless but can enlarge and prolapse through the anal canal. The person will have bright red blood and pruitis.

41
Q

How do you treat haemorrhoids?

A
  1. Increase hydration. and fibre in diet.
  2. Avoid straining.
  3. Rubber band ligation (cut off blood supply).
  4. Surgery.
42
Q

What are external haemorrhoids?

A

Symptomatic anal cushions that occur below the pectinate line. They are swellings of the anal cushions that can thrombose. They are very painful but with surgery they have good outcomes.

43
Q

What are anal fissures?

A

Linea tear in the anoderm (mucosa of the anus) as a result of passing a hard stool. Causes severe pain on fecaecation and haematochezia.

44
Q

What causes anal fissures?

A

High internal anal sphincter tone which reduces blood flow to the anal mucosa.

45
Q

How do we treat anal fissures?

A
  1. Hydration, dietary fibre, analgesia.
  2. Warm bath.
  3. Medication to reduce high internal sphincter anal tone.
46
Q

What are the common causes of haematochezia (passing fresh blood)?

A
  1. Diverticulitis.
  2. Angiodysplasia (small vascular malformation in the bowel wall).
  3. Ulcerative colitis.
  4. Colorectal cancer.
  5. Anorectal disease- haemorrhoids and anal fissure.
  6. Upper `GI bleeding- large bleeding with fast transit.
47
Q

What is melaena?

A

Black tarry stools that are often smelly. They are due to haemoglobin being altered by digestive enzymes and the gut bacteria.

48
Q

What are the common causes of Malaena?

A

Upper GI bleeding:

  1. Peptic ulcer disease.
  2. Variceal bleeds.
  3. Upper GI malignancy.
  4. Oesophageal/gastric cancer.
49
Q

What are the uncommon causes of Malaena?

A
  1. Gastritis.
  2. Meckel’s diverticulum.
  3. Iron supplements.

Gastrointestinal (10 decks)

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