Right iliac fossa differential: appendicitis, mesenteric adenitis, Meckel diverticulitis, terminal ileitis, caecal pathology, ovarian torsion, ruptured ectopic, ovarian cyst, ureteric colic, inguinal hernia. Lifetime risk of appendicitis is 7-8 per cent.
The four mechanisms framework
Classify by mechanism: inflammation, obstruction, perforation, or ischaemia. Every acute abdominal presentation fits one. This helps you order investigations logically and signals structured thinking.
Always mention pregnancy testing in any woman of reproductive age with abdominal pain. Missing an ectopic pregnancy is one of the highest-yield medicolegal issues in emergency surgery.
The investigation hierarchy
Bedside first: observations, urinalysis, pregnancy test, ECG, glucose. Bloods: FBC, U&E, CRP, LFTs, amylase, group and save, VBG with lactate. Imaging guided by suspicion: erect chest X-ray for perforation, ultrasound for women of reproductive age and biliary pathology, CT for most other presentations.
Red flags that change management
Generalised peritonitis with guarding warrants immediate surgical input. Lactate above 2 mmol/L raises concern for ischaemia. Pain disproportionate to findings suggests mesenteric ischaemia until proven otherwise. Haemodynamic instability demands escalation.
The MRCS station structure
Focused history (SOCRATES), examination findings, differentials ranked by likelihood, investigations with justification, initial management including resuscitation and senior input. Visual frameworks for all 22 acute presentations are in SurgAtlas at surgatlas.com.