Because I might as well make use of this blog to impart some knowledge to random readers...

Incidence: Most common surgical emergency (lifetime incidence = 6%)

Pathogenesis: lumen obstruction --> gut organisms invade --> oedema, ischaemic necrosis, perforation

Symptoms: Periumbilical (around the umbilicus) pain that radiates to RIF [ early inflammation --> irritates structure and walls of appendix --> colicky pain referred to mid abdomen/periumbilical --> continued inflammation --> irritation of parietal peritoneum --> somatic, lateralised pain settles @ McBurney's point (2/3 from umbilicus to right ASIS) ] anorexia, vomiting (rarely prominent), constipation, diarrhoea

O/E:

General signs: Tachycardia, Febrile, Furred tongue, Lying still (movement aggravates), Coughing hurts, shallow breaths, foetor.

Abdominal palpation: RIF - guarding, rebound tenderness, percussion tenderness

Special tests: Rovsing's sign (pain in RIF when LIF is pressed), Psoas sign (pain on extending hip if retrocaecal appendix), Cope sign (pain on flexion and internal rotation of right hip if appendix is close relation to obturator internus)

Investigations: FBC (check anaemia, WBC, CRP), USS, CT Abdo

Treatment: Appendicectomy. Start antibiotics (metronidazole 500mg/8hr + cefuroxime 1.5g/8hr, 1 to 3 doses IV starting 1 hour pre-op --> reduce wound infections)

Differential diagnoses: ectopic? UTI? mesenteric adenitis? cystitis? cholecystitis? diverticulitis? salpingitis/PID? dysmenorrhea? Crohn's? Perforated ulcer? food poisoning? meckel's diverticulum?

Complications: perforation, appendix mass --> inflamed appendix covered with omentum, appendix abscess --> appendix mass that fails to resolve