Distal GI Tract Pathology

Question 1

Explain the differences between the two main types of diarrhoea. (5)

Answer 1

Secretory - secretion of Cl- and HCO3- (infection) or too little absorption of Ma+ (reduced SA). Cannot be stopped actively.
Osmotic - lumen contains too much osmotic material that is poorly absorbed so water cannot leave (lactose intolerance). Can be stopped if offending thing is not eaten.

Question 2

Define constipation (3)

Answer 2

Straining, hard stools, less often, feelings of incomplete evacuation, obstruction.

Question 3

Define diarrhoea (2)

Answer 3

Loose or watery stools that occur more than 3 times in a day.

Question 4

Describe risk factors for constipation (4)

Answer 4

Female
Medications
Immobility
Very young / very old.

Question 5

Casuses of constipation. (3)

Answer 5

Transit issues due to psychological stress.
Slowed colonic transport - dilated colon or less peristalsis eg due to MS.
Defication muscle coordination issues

Question 6

Treatments of constipation. (4)

Answer 6

Increase fluid intake
Increase activity
Increase fibre
Laxatives.

Question 7

Describe the appendix (3)

Answer 7

A diverticulum off the caecum with a complete longitudinal layer of muscle unlike the teniae coli of the colon.

Question 8

Describe presentation of appendicitis. (6)

Answer 8

Umbilical pain radiating to the right iliac fossa
Anorexia
Fever
Nausea
Rebound tenderness on McBurney’s point (2/3 of the way from umbilicus to ASIS).

Question 9

Causes of appendicitis (2)

Answer 9

Blockage created pressure in the appendix causing oedema causing ischaemia
Viral or bacterial infection causes mucosal changes.

Question 10

Investigations of appendicitis (4)

Answer 10

Bloods for high WCC
Urine dip for UTI
Pregnancy test for ectopic
CT scan shows appendix doesn’t fill with contrast.

Question 11

Describe diverticulosis (5)

Answer 11

Asymptomatic
Occurs in the colon when outpouchings of mucosa and submucosa herniate through the muscle layers.
Occurs when vasa recta penetrate the bowel wall due to high intra-luminal pressure (low fibre)

Question 12

Describe diverticular disease (2)

Answer 12

Diverticular become painful but not inflamed or infected.

Question 13

Describe acute diverticulitis (2)

Answer 13

Diverticula become inflamed and perforate possibly with bleeding and abscess formation.

Question 14

Signs and symptoms of acute diverticulitis. (6)

Answer 14

Localised abdominal tenderness (LLQ)
Reduced bowel sounds
Fever
Bloating
Constipation
Haematochezia

Question 15

Describe the investigations of diverticulosis. (4)

Answer 15

Blood tests WCC
Pregnancy test
USS and CT
Careful colonoscopy - don’t want to make it worse

Question 16

Describe the rectum (4)

Answer 16

15cm long, passes through pelvic floor, continuous bands of longitudinal muscle. Acts as a temporary store.

Question 17

Describe the vascular supply to the rectum. (5)

Answer 17

Arterial supply
Superior rectal - IMA
Middle rectal - internal iliac
Inferior rectal - pudendal

Venous drainage
Systemic - superior rectal
Portal - internal iliac

Question 18

Describe how the anal canal is used in continance. (4)

Answer 18

Distensible rectum
Normal anorectal angle (rectum anteriorly, anal canal posteriorly)
Anal cushions
Normal anal sphincters

Question 19

Describe the pectinate / dentate line. (4)

Answer 19

Boundary between the hindgut rectum (columnar and visceral) and the anal canal (stratified squamous and somatic).

Question 20

Describe the anal sphincter complex (4)

Answer 20

Internal involuntary sphincter - thickening of smooth muscle under autonomic control.
External anal sphincter - striated muscle, voluntary, pudendal nerve.

Question 21

Describe the different types of haemorrhoids. (4)

Answer 21

Internal - symptomatic anal cushions above pectinate line. Relatively painless, can enlarge and prolapse, bleed bright red.
External - below pectinate line swellings of anal cushions that may thrombose. Very painful - somatic.

Question 22

Describe treatments of haemorrhoids. (4)

Answer 22

Increased fibre and hydration
Avoid straining
Surgery
Rubber band ligation

Question 23

Describe an anal fissure. (5)

Answer 23

Linear tear in anoderm following constipation or diarrhoea. Caused by increased internal anal sphincter tone and ischaemia. Treated by baths, hydration and analgesia.

Question 24

Explain the differences between haematochezia and malaena. (6)

Answer 24

Haematochezia - bright red blood in stools from usually a distal pathology - diverticulitis, colorectal cancer, haemorrhoids, very fast transit upper GI bleed.
Malaenia - the more common manifestation of upper GI bleeding. Black, tarry, smelly stools due to Hb being metabolised by gut bacteria. Caused by peptic ulcers, upper GI malignancy, variceal bleeds.