Appendicitis

Question 1

Surface and Internal landmarks for appendix

Answer 1

Note: this is for the base of the appendix which not variable in location unlike the tip of the appendix

Surface: McBurney’s point
1/3 between ASIS and umbilicus

Internal: 2cm inferior to the ileocaecal valve

Question 2

Physical examination findings consistent with Appendicitis

Answer 2

Rebound tenderness, reduced bowel sounds, guarding
McBurney’s point tenderness
(Depending on the location of the tip of the appendix:
Rovsing’s sign - left sided palpation causes right sided pain
Psoas sign - flex hip and causes irritation to the psoas –> retrocaecal orientation)

Question 3

Name the possible appendiceal tip orientations

Answer 3

Commonly - retrocolic
paracolic
pelvic, pre-ileal, post-ileal

Question 4

Pathophysiology of pain and appendicitis

Answer 4

Embryologically umbilicus and appendix originate from the same spinal segment T10. During acute inflammation, the somatic fibres are innervated and there is referred pain. + secondary to local distension

Imbalance between acid-pepsin secretions and normal host mucosal defence mechanisms (parietal cells on mucosa layer of bowel)

1. Acute obstruction of luminal appendix
2. Mucous build-up serves as a medium for GI bacterial colonisation e.g. E Coli, Bacteroides Fragilis
3. Inflammatory response - swelling and engorgement +/- ischemia/infarction/perforation/penetration posteriorly

Question 5

Complications

Answer 5

Acute: haemorrhage, anemia, perforation, penetration, ischemia, hypovolemic shock

Subacute: liver abscess (due to venous drainage into the hepatic sinusoids)

Chronic: Adhesions; bowel obstruction, malignant transformation

Question 6

How does H Pylori cause appendicitis?

Answer 6

Virulence factors: Cyclotoxin-associated gene A, protease and phospholipase
Protective factors: Urease - release ammonia to neutralise acidic environment