14 - Distal GI Pathology

Question 1

What is the anatomy of the rectume?

Answer 1

• Curved shape anterior to sacrum
• Parts are extra-peritoneal
• Temporarily stores faeces and stretching stimulates urge to defecate

Question 2

What is the blood supply and drainage of the rectum?

Answer 2

Question 3

Where does the anal canal start?

Answer 3

• Proximal border of anal sphincter complex
• Puborectal sling cause rectum to go from being anterior to anal canal being posterior. Helps continence

Question 4

What factors are needed to maintain fecal continence?

Answer 4

Question 5

What is the anal sphincter complex made up of?

Answer 5

Internal involuntary sphincter: thickening of smooth circular muscle. Autonomical control, 80% continence

External striated sphincter: three layers of muscle supplied by pudendal nerve. 20% of continence

Question 6

What is the defecation reflex and what are the possible consequences of this reflex?

Answer 6

Faeces moves into anal canal to see if appropriate to be expelled

Question 7

What is the dentate line of the anal canal, and what is the relevance of this?

Answer 7

• Junction of hindgut and proctodaeum
• Above is visceral and columnar so doesn’t feel pain unless stretch
• Below is somatic and stratified sqaumous

Question 8

What are anal cushions?

Answer 8

• Venous plexus divided into three areas
• Swell to help continence
• When enlarged this is haemorrhoids

Question 9

What are internal haemorrhoids and how are they treated?

Answer 9

• • Above dentate line* and covered in transitional or columnar mucosa
• Produce symptoms when lose CT support and prolapse through anal canal
• Painless until prolapse and then may bleed bright red or itch

Treat: increase hydration, fibre, avoid straining, rubber band ligation, surgery. INITIALLY SOFTEN STOOL

Question 10

What are external haemorrhoids and how are they treated?

Answer 10

• Visible at anal verge and often residual skin from previous episodes of haemorrhoid inflammation
• Usually asymptomatic and no bleeding but symptoms when thrombosis
• Patient often has issues with hygiene due to folds of skin, itching and inflammation

Question 11

What is an anal fissure, what are the causes and how do we treat it?

Answer 11

- Linear tear in anoderm, usually after a large hard bowel movement.

• Extremely painful when trying to pass further stools
• Patient may have bleeding
• Treat by increasing fibre and water intake, hygeine and comfort

Question 12

What is haematochezia?

Answer 12

• High flow bleeding from upper GI or lower GI bleeding so bright red blood in stools
• Diverticulitis is most comon cause but can also be caused by polyps, cancer, colitis, anorectal disorders

Question 13

What is melaena?

Answer 13

• Black tarry stools that are offensive smelling. Due to Hb being altered by digestive enzymes and gut bacteria

Question 14

Why do we have to repeat an endoscopy for coeliac diagnosis?

Answer 14

Due to autoimmune antibodies against gliadin fraction of gluten. Causes villi to flatten.

3 months not trigger can see changes reverting to normal on colonoscopy

Question 15

What are some causes of B12 deficiency?

Answer 15

• Crohn’s
• Poor intake e.g vegetarian
• Don’t secrete as much acid e.g PPIs and H2RBs
• Pernicious anaemia

Question 16

What is the pain associated with gallstones called?

Answer 16

• Biliary colic , no inflammation
• Pain after eating as lipids stimulate CCK release so gallbladder contracts. Can still get bile from liver though
• Pain in right

Question 17

What are some complications of the common bile duct being blocked?

Answer 17

• Pancreatitis
• Jaundice
• Cholangitis

Question 18

How does alcoholic fatty liver disease occur?

Answer 18

• Increased TAG deposits as lack of lipoproteins to carry fats and increased NADH prevents fats being metabolised

Question 19

Why can alcohol misuse lead to malnutrition and vitamin deficiencies?

Answer 19

• Lack of appetite
• Liver damage so no vitamin synthesis
• Alcoholic pancreatitis
• Gatritis