Surgery Surgery · Clinical · High Yield

Appendicitis

Appendicitis is the most common surgical emergency. Its diagnosis combines clinical features, inflammatory markers, and imaging — all of which can be remembered systematically.

✦ The Mnemonic

"APPENDIX Captures Every Classic Feature"

Eight clinical and diagnostic features of acute appendicitis

A Anorexia Near-universal early feature; loss of appetite precedes pain in most cases

P Pain (central → RIF) Begins periumbilical (visceral); migrates to RIF (somatic) as peritoneum inflamed

P Pyrexia Low-grade fever 37.5–38.5°C; high fever suggests perforation or abscess

E Elevated WCC Leucocytosis — typically 11–18 × 10⁹/L; CRP elevated

N Nausea ± Vomiting Usually after pain onset — vomiting before pain suggests gastroenteritis instead

D Direct tenderness (RIF) McBurney's point; maximal tenderness 1/3 ASIS to umbilicus

I Iliopsoas sign Pain on passive hip extension — inflamed appendix lying on psoas

X Xtra signs Rovsing's sign (LIF palpation causes RIF pain); guarding; rebound tenderness

📚 Clinical Breakdown

The Alvarado score (0–10) quantifies the probability of appendicitis: migration of pain (1), anorexia (1), nausea (1), RIF tenderness (2), rebound (1), elevated temp (1), leucocytosis (2), left shift (1). Score ≥7 = high probability; score <4 = low probability. CT has ~95% sensitivity and is used in diagnostic uncertainty.

The order of symptom onset is crucial: anorexia → central pain → nausea → RIF migration → vomiting → fever. Vomiting before pain strongly suggests an alternative diagnosis (e.g., gastroenteritis). This sequence reflects visceral then somatic peritoneal involvement.

Complications: perforation (10–30% in adults, higher in elderly and children), appendix abscess (walled-off perforation — treat with antibiotics ± IR drainage then interval appendicectomy), and pylephlebitis (septic portal vein thrombosis — rare but fatal if missed).

McBurney's point 1/3 from ASIS to umbilicus

Rovsing's sign LIF palpation → RIF pain

Psoas sign Inflamed appendix on psoas — pain on hip extension

Most common complication Perforation

⭐ Clinical Pearl

Imaging choice: ultrasound first in children and pregnant women (no radiation, sensitivity ~86%). CT abdomen/pelvis with contrast is the gold standard in adults (sensitivity ~95%). A non-visualised appendix on ultrasound does NOT exclude appendicitis — proceed to CT or MRI if clinical suspicion persists.

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