Appendicitis

Question 1

Describe the anatomy of the appendix.

Answer 1

The appendix is a blind ending tube from 2-20cm in length (avg 9cm).
Arises from posteromedial wall of caecum.

Question 2

How may the appendix position vary anatomically?

Answer 2

Varies:

• retrocaecal (65%)
• pelvic (projects down) (31%)
• subcaecal (immediately below caecum) (2%)
• pre-ileal (front of terminal ileum) (1%)
• post-ileal (behind ileum) (0.4%)

Question 3

How is the appendix supplied (vasculature)?

Answer 3

Appendicular artery (branch of ileocolic). 
Runs behind terminal ileum to reach base of appendix; extends to tip in mesoappendix.

Question 4

Describe the histology of the appendix.

Answer 4

• Mucosa similar to colon: columnar with crypts and mucous secreting glands
• Extensive lymphoid tissue in lamina propria (lymphocytes forming lymphoid follicles, eosinophils, macrophages).
• Outer layers formed from inner (circular) and outer (longitudinal) smooth muscle of caecum. Covered by series.

Question 5

What is the patholophysiology of appendicitis?

Answer 5

obstruction of appendicular lumen (faecolith or oedema). Bacteria multiply distally increasing pressure. Blood supply compromised -> gangrene. May rupture OR be walled off by omentum and form an abscess.

Question 6

Describe the symptoms of appendicitis.

Answer 6

-Initial: visceral central abdominal pain; + anorexia, N/V
-Later: continued peritoneal irritation causes parietal pain in RIF.
May also have urinary symptoms if inflamed appendix is near to bladder/ureter.

Question 7

What are the examination features of appendicitis?

Answer 7

-Coated tongue and foul breath with mild pyrexia (classic but not always)
-Tenderness and guarding at McBurney’s point
(for appendix medial to caecum)