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EM TopicsAcute appendicitis

EM · Acute appendicitis

Acute appendicitis

Also known as Acute appendicitis · Appendiceal obstruction · Perforated appendix · Appendiceal abscess

Acute appendicitis — luminal obstruction progressing to perforation in 16 to 40 per cent; central pain migrating to the right iliac fossa with anorexia, nausea, fever and localised RIF tenderness; the Alvarado (MANTRELS) and AIR scores with WSES risk-stratified imaging; laparoscopic appendicectomy first-line with ceftriaxone 2 g 24-hourly plus metronidazole 500 mg 6-hourly empiric cover. ACEM-primary, globally tagged.

high14 referencesUpdated 26 July 202624 min readSource-verified · Oct 2026

Checked against its sources on 14 Oct 2026

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ACEMFRCEMABEMFRCPCCCFPEMEBEEM

Red flags

  • A perforated appendix carries a mortality around 5 per cent against under 0.1 per cent for non-gangrenous disease — the window to operate is short and the septic patient needs the simultaneous resuscitation and the theatre
  • Every woman of reproductive age with right iliac fossa pain has an ectopic pregnancy and a torsion until the beta-hCG and the ultrasound exclude them
  • The elderly, the diabetic, the immunosuppressed and the pregnant patient frequently present with atypical or muted pain — the diagnosis is missed and the perforation is more common
  • The appendiceal mass or abscess in the delayed presentation is often managed conservatively with the antibiotics and the interval appendicectomy, not the immediate surgery
  • A normal WCC and CRP together make appendicitis unlikely — but an inflamed appendix on imaging with compatible pain is appendicitis regardless of the bloods
On this page

Related topics

  • Acute abdominal pain — the emergency department approach
  • Biliary disease — biliary colic, acute cholecystitis and ascending cholangitis
  • Renal colic and nephrolithiasis
  • Ectopic pregnancy
  • Acute pancreatitis
  • Testicular torsion
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Your progress

Saved on this device.

Practise this topic8 MCQs with explanations

Target exams

ACEMFRCEMABEMFRCPCCCFPEMEBEEM

Red flags

  • A perforated appendix carries a mortality around 5 per cent against under 0.1 per cent for non-gangrenous disease — the window to operate is short and the septic patient needs the simultaneous resuscitation and the theatre
  • Every woman of reproductive age with right iliac fossa pain has an ectopic pregnancy and a torsion until the beta-hCG and the ultrasound exclude them
  • The elderly, the diabetic, the immunosuppressed and the pregnant patient frequently present with atypical or muted pain — the diagnosis is missed and the perforation is more common
  • The appendiceal mass or abscess in the delayed presentation is often managed conservatively with the antibiotics and the interval appendicectomy, not the immediate surgery
  • A normal WCC and CRP together make appendicitis unlikely — but an inflamed appendix on imaging with compatible pain is appendicitis regardless of the bloods
The one-line answer

Acute appendicitis is among the most common causes of acute abdominal pain, with lifetime risk 9 per cent in the USA — and presents as central pain that migrates to the right iliac fossa with anorexia, nausea, and localised right-lower-quadrant tenderness (Alvarado's top-weighted factor). Risk-stratify with the AIR score (WSES Rec 1.4, Grade 1A; ROC 0.86 versus Alvarado 0.79), image by risk (scores identify intermediate-risk patients needing imaging, Rec 1.2.1), and refer for laparoscopic appendicectomy with ceftriaxone 2 g 24-hourly plus metronidazole 500 mg 6-hourly empiric cover. [1][1] [2][2] [7][7] The mantra: the migration is the discriminator, the AIR score risk-stratifies, the beta-hCG is non-negotiable in every woman.[1][2][7]

Meet the patient

A young man arrives with central abdominal pain that moved to the right iliac fossa hours ago. He is anorexic, nauseated, vomited once, and lies perfectly still on the trolley. The right iliac fossa is tender with voluntary guarding and rebound. The pain that moved is the feature that earns the diagnosis — migration from the periumbilical region to the right iliac fossa is the clinical hallmark of appendicitis.[1]

Two questions decide his next hour: is this appendicitis or a mimic? (the beta-hCG and the AIR score sort the differential) and how sick is he? (the perfusion, the lactate, and the peritonism decide the urgency). Hold those two questions and the management slots into place.[1]

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References14ShowHide
  1. [1]Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med, 1986.PMID 3963537
  2. [2]Andersson RE, Stark J. Diagnostic value of the appendicitis inflammatory response (AIR) score. A systematic review and meta-analysis. World J Emerg Surg, 2025.PMID 39923099
  3. [3]Andersson M, Kolodziej B, Andersson RE Validation of the Appendicitis Inflammatory Response (AIR) Score. World J Surg, 2021.PMID 33825049
  4. [4]Salminen P, Paajanen H, Rautio T, Nordström P, Aarnio M, Rantanen T, et al. Antibiotic Therapy vs Appendectomy for Treatment of Uncomplicated Acute Appendicitis: The APPAC Randomized Clinical Trial. JAMA, 2015.PMID 26080338
  5. [5]Flum DR, Davidson GH, Monsell SE, et al. A Randomized Trial Comparing Antibiotics with Appendectomy for Appendicitis. N Engl J Med, 2020.PMID 33017106
  6. [6]Doria AS, Moineddin R, Kellenberger CJ, Epelman M, Beyene J, Schuh S, et al. US or CT for Diagnosis of Appendicitis in Children and Adults? A Meta-Analysis. Radiology, 2006.PMID 16928974
  7. [7]Di Saverio S, Podda M, De Simone B, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg, 2020.PMID 32295644
  8. [8]Ranji SR, Goldman LE, Simel DL, Shojania KG. Do opiates affect the clinical evaluation of patients with acute abdominal pain? JAMA, 2006.PMID 17032990
  9. [11]Ohle R, O'Reilly F, O'Brien KK, et al. The Alvarado score for predicting acute appendicitis: a systematic review. BMC Med, 2011.PMID 22204638
  10. [12]Addiss DG, Shaffer N, Fowler BS, et al. The epidemiology of appendicitis and appendectomy in the United States. Am J Epidemiol, 1990.PMID 2239906
  11. [13]Dsouza R, Osueni A, Menon G. Appendiceal Tumors. StatPearls, 2025.PMID 32310403
  12. [14]Tracey M, Fletcher HS. Appendicitis in pregnancy. Am Surg, 2000.PMID 10888131
  13. [15]Mangi AA, Berger DL. Stump appendicitis. Am Surg, 2000.PMID 10966030
  14. [16]Fusaro L, Di Bella S, Martingano P, et al. Pylephlebitis: A Systematic Review on Etiology, Diagnosis, and Treatment of Infective Portal Vein Thrombosis. Diagnostics (Basel), 2023.PMID 36766534

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Related topics

  • Acute abdominal pain — the emergency department approach
  • Biliary disease — biliary colic, acute cholecystitis and ascending cholangitis
  • Renal colic and nephrolithiasis
  • Ectopic pregnancy
  • Acute pancreatitis
  • Testicular torsion