Appendicitis

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Quick Overview

Appendicitis is the most common surgical emergency, affecting ~7% of the population. Diagnosis relies on clinical scoring systems (Alvarado, AIR), selective imaging, and management pathways ranging from antibiotic-first approaches to emergency appendicectomy. NICE NG141 emphasizes risk stratification and evidence-based decision-making for optimal outcomes.

Core Facts & Concepts

Clinical Scoring Systems:

ScoreComponentsInterpretation
AlvaradoMigration of pain (1), Anorexia (1), Nausea/vomiting (1), RIF tenderness (2), Rebound (1), Fever >37.3°C (1), Leukocytosis (2), Left shift (1)≤4: low risk; 5-6: moderate; ≥7: high probability
AIRVomiting (1), RIF pain (1), Rebound/guarding (1-3), Temp >38.5°C (1), WCC 10-14.9 (1) or ≥15 (2), CRP 10-49 (1) or ≥50 (2)0-4: low; 5-8: intermediate; 9-12: high

Key Thresholds:

  • Imaging indication: Alvarado 5-6 or AIR 5-8 (diagnostic uncertainty)
  • First-line imaging: Ultrasound (children/women of childbearing age); CT if inconclusive
  • Appendix diameter: >6mm on imaging suggests appendicitis
  • Complicated appendicitis: Perforation, abscess (>3cm), or gangrene

Figure 1: CT scan showing dilated fluid-filled appendix with periappendiceal fat stranding

Management Pathways (NICE NG141):

  • Uncomplicated appendicitis: Appendicectomy within 24 hours OR antibiotic-first approach (if patient preference, suitable for conservative management)
  • Antibiotics: Co-amoxiclav 1.2g IV TDS OR cefuroxime 1.5g + metronidazole 500mg IV TDS
  • Complicated with abscess <3cm: Immediate appendicectomy
  • Abscess ≥3cm: Percutaneous drainage + IV antibiotics → interval appendicectomy at 6-8 weeks

Problem-Solving Approach

Diagnostic Workflow:

  1. Clinical assessment: RIF pain, migration from periumbilical region, fever, anorexia
  2. Calculate Alvarado/AIR score to stratify risk
  3. Low scores (Alvarado ≤4, AIR 0-4): Discharge with safety-netting; consider alternative diagnoses
  4. Intermediate scores (Alvarado 5-6, AIR 5-8): Arrange imaging within 4 hours
  5. High scores (Alvarado ≥7, AIR 9-12): Proceed to appendicectomy without routine imaging

Figure 2: Ultrasound showing non-compressible appendix with target sign appearance

🚩 Red Flags for Complicated Appendicitis:

  • Symptoms >48 hours
  • Palpable RIF mass
  • Systemic sepsis (HR >90, temp >38°C, rigors)
  • Peritonism with guarding/rigidity

Decision Points:

  • Antibiotic-first vs surgery: Offer antibiotics if uncomplicated + patient preference; warn 30% recurrence at 1 year
  • Laparoscopic vs open: Laparoscopic preferred (faster recovery, less wound infection) unless hemodynamically unstable
  • Interval appendicectomy: Mandatory after conservative management of abscess (exclude malignancy in >40 years)

Analysis Framework

Differential Diagnosis Discriminators:

ConditionKey FeaturesDistinguishing Test
AppendicitisRIF pain, fever, raised WCC/CRPCT: inflamed appendix >6mm
Ectopic pregnancyAmenorrhea, +βhCG, shoulder tip painTransvaginal USS
Ovarian torsionSudden severe pain, vomiting, adnexal massDoppler USS: absent flow
Mesenteric adenitisURTI preceding, mobile tendernessCT: enlarged mesenteric nodes
Crohn's diseaseChronic symptoms, diarrhea, weight lossMRI enterography

Clinical Pearl: Psoas sign (pain on right hip extension) and obturator sign (pain on internal rotation) suggest retrocaecal/pelvic appendicitis.

Visual Aid

Key Points Summary

Alvarado ≥7 or AIR 9-12: Proceed to surgery without imaging (high probability)

Imaging threshold: Scores 5-6 (Alvarado) or 5-8 (AIR) warrant USS/CT within 4 hours

Antibiotic-first: Valid for uncomplicated appendicitis; 30% recurrence rate at 1 year

Abscess ≥3cm: Percutaneous drainage + interval appendicectomy at 6-8 weeks (not immediate surgery)

Laparoscopic preferred: Lower wound infection, faster recovery unless unstable

Negative appendicectomy rate: Acceptable at 15-20% to avoid missed diagnoses

>40 years with mass: Interval appendicectomy mandatory to exclude caecal malignancy

Practice Questions: Appendicitis

Test your understanding with these related questions

A 64-year-old man presents with progressive memory loss, gait instability, and urinary incontinence. MRI shows ventricular dilatation. CSF opening pressure is 12 cmH₂O. What is the most appropriate treatment?

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Flashcards: Appendicitis

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Infective endocarditis causing congestive cardiac failure is an indication for _____

TAP TO REVEAL ANSWER

Infective endocarditis causing congestive cardiac failure is an indication for _____

emergency valve replacement surgery

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