What are the clinical features of appendicitis?

Clinical Features of Appendicitis

Classic Presentation

The diagnosis of acute appendicitis is primarily clinical, with the classic presentation including periumbilical pain that migrates to the right lower quadrant, accompanied by anorexia, nausea/vomiting, and fever—though this complete constellation occurs in only approximately 50% of cases. 1, 2

Symptom Progression

The characteristic sequence unfolds as follows:

• Initial vague periumbilical or epigastric pain that is poorly localized 1, 2
• Anorexia (often the first symptom) 2
• Nausea with intermittent, non-sustained vomiting 1
• Pain migration to the right lower quadrant within 12-24 hours 3, 1
• Low-grade fever (typically present but not high-grade) 2, 4

Physical Examination Findings

In adults, the most reliable signs for ruling in appendicitis are right lower quadrant pain, abdominal rigidity, and periumbilical pain radiating to the right lower quadrant. 4

Key examination findings include:

• Localized tenderness in the right lower quadrant (most consistent finding) 3, 4
• Positive psoas sign (increased pain with right hip extension, suggesting retrocecal appendix location) 3, 4
• Positive obturator sign (pain with internal rotation of flexed right hip) 4
• Positive Rovsing sign (right lower quadrant pain with left lower quadrant palpation) 4
• Rebound tenderness and guarding indicating peritoneal irritation 3, 1

Important Clinical Caveats

The presence of vomiting before pain onset makes appendicitis unlikely and should prompt consideration of alternative diagnoses. 3

Fever and migratory pain to the right lower quadrant significantly increase the likelihood of appendicitis. 3

Atypical Presentations

Clinical presentation is often inconsistent, and atypical presentations are common, particularly in certain populations. 3

Special Populations

• Children under 5 years: Symptoms are typically atypical, leading to higher perforation rates due to delayed diagnosis 1
• Pregnant patients: The appendix is displaced upward by the enlarging uterus, causing pain in the upper quadrant or entire right side rather than the classic right lower quadrant location 5
• Elderly patients: May present with minimal symptoms despite advanced disease 3

Laboratory Findings

Laboratory evaluation reveals leukocytosis with left shift (segmented neutrophils >75%) in most cases. 3

• Complete blood count showing elevated white blood cell count with neutrophil predominance 3
• C-reactive protein elevation (incorporated into the AIR score for enhanced diagnostic accuracy) 3

Clinical Scoring Systems

The Alvarado score and Appendicitis Inflammatory Response (AIR) score stratify patients into low, moderate, or high probability categories to guide management decisions. 3, 4

Alvarado Score Interpretation:

• Score 5-6: Compatible with appendicitis 3
• Score 7-8: Probable appendicitis 3
• Score 9-10: Very probable appendicitis 3

These scoring systems help identify low-risk patients who may not require imaging or surgery, high-risk patients who can proceed directly to surgical management, and intermediate-risk patients who require diagnostic imaging. 1, 4

Diagnostic Imaging Approach

Early clinical evaluation is essential, but a step-up diagnostic approach should be employed, beginning with clinical and laboratory examination and progressing to imaging when the diagnosis is uncertain. 3

Imaging Algorithm:

• First-line: Point-of-care ultrasound in adults when imaging is indicated 6
• Second-line: Contrast-enhanced CT (preferably without oral contrast to avoid delays) if ultrasound is inconclusive, with sensitivity 85.7-100% and specificity 94.8-100% 3, 6, 1, 2
• Third-line: Diagnostic laparoscopy if imaging remains inconclusive but clinical suspicion persists 3, 6

CT imaging is particularly important in obese patients, where ultrasound has limited diagnostic performance with higher false diagnosis rates (46.2% vs 38.5% in non-obese females). 6

Complications and Red Flags

Delays in diagnosis lead to complications including gangrene, perforation, appendiceal mass, and peritonitis, which prolong hospital stay and increase mortality risk. 3

Signs of complicated appendicitis or sepsis include:

• Hypotension and signs of hypoperfusion (oliguria, altered mental status, lactic acidosis) 3
• Tachycardia and tachypnea indicating systemic inflammatory response 3
• Prolonged symptom duration (>4 days associated with 60% perforation rate in some populations) 3