What is the appropriate assessment and management for a patient suspected of having appendicitis?

Assessment and Management of Suspected Appendicitis

Use a risk-stratified clinical approach combining symptoms, physical examination, and laboratory findings to guide imaging decisions, with CT abdomen/pelvis with IV contrast as the primary diagnostic tool in non-pregnant adults, followed by prompt surgical consultation and broad-spectrum antibiotics once appendicitis is confirmed. 1, 2, 3

Initial Clinical Risk Stratification

Begin by systematically assessing specific clinical predictors to categorize patients into low, intermediate, or high probability groups. 1

High-Risk Clinical Features (Proceed Directly to Surgical Consultation)

• Periumbilical pain migrating to right lower quadrant 4, 5
• Rebound tenderness or abdominal rigidity 5
• Positive psoas sign, obturator sign, or Rovsing sign 5
• Fever >38°C combined with focal right lower quadrant tenderness 1

Intermediate-Risk Features (Obtain Imaging)

• Right lower quadrant pain without clear peritoneal signs 1
• Nausea with focal abdominal tenderness 1
• Equivocal physical examination findings 1

Low-Risk Features (Consider Discharge with 24-Hour Follow-up)

• Vomiting before pain onset (makes appendicitis less likely) 2
• Absence of right lower quadrant tenderness 1
• Normal vital signs with minimal laboratory abnormalities 1

Laboratory Testing Strategy

Obtain WBC with differential and C-reactive protein in all patients with suspected appendicitis. 2

• WBC >10,000/mm³ AND CRP ≥8 mg/L combined has the strongest predictive value (positive likelihood ratio 23.32, negative likelihood ratio 0.03) 1
• WBC >15,000/mm³ alone has positive likelihood ratio of 3.47 1
• Isolated WBC elevation has limited value (positive likelihood ratio only 1.59-2.7) 1
• CRP ≥10 mg/L alone has positive likelihood ratio of 4.24 1

Critical pitfall: Do not rely on WBC count alone—it misses appendicitis in many cases. The combination with CRP is far more powerful. 1

Clinical Scoring Systems

Apply the Alvarado score (adults) or Pediatric Appendicitis Score (children) to systematically integrate clinical findings, but never use these scores alone to confirm appendicitis. 1, 2

Alvarado Score Interpretation

• Score ≤3: Very low probability—consider discharge with 24-hour follow-up 1
• Score 4-6: Intermediate probability—obtain imaging before any surgical decision 1
• Score ≥7: High probability—surgical consultation with or without imaging 1

Major caveat: Low Alvarado scores do NOT reliably exclude appendicitis. Studies show 8.4% of confirmed appendicitis cases had scores below 5, and one study found 72% of patients with scores 1-4 ultimately had appendicitis. 1 Elderly patients and very young children are particularly prone to atypical presentations with low scores. 1

Imaging Strategy by Patient Population

Non-Pregnant Adults (Standard Approach)

CT abdomen and pelvis with IV contrast is the primary imaging modality. 1, 2, 3

• Sensitivity: 96-100% 1, 2
• Specificity: 93-95% 1, 2
• IV contrast is essential—it increases sensitivity to 96% compared to unenhanced CT 1
• Oral contrast is NOT necessary and delays diagnosis—IV contrast alone provides excellent accuracy 1, 2

Technical specifications from the evidence: CT with oral and IV contrast showed 100% sensitivity (negative likelihood ratio 0) versus 90% sensitivity for CT without contrast (negative likelihood ratio 0.12), though this difference did not reach statistical significance in one study. 1 However, another Class I study demonstrated that IV contrast improved sensitivity from 76% to 91%. 1

Children and Adolescents

Ultrasound is the first-line imaging modality to avoid radiation exposure. 2, 3

• Sensitivity: 76% (formal ultrasound) to 91% (point-of-care ultrasound by emergency physicians) 2
• Specificity: 95-97% 2
• Key ultrasound findings: appendiceal diameter ≥7 mm, non-compressibility, focal tenderness 2

If ultrasound is non-diagnostic and clinical suspicion persists, proceed to MRI or low-dose CT with contrast. 2

Pregnant Patients

Ultrasound is the initial imaging modality; if inconclusive, use MRI without IV contrast (NOT CT). 2, 3

• MRI sensitivity: 94%, specificity: 96% 2
• Avoid CT in first trimester due to radiation risk 3

Elderly Patients

CT scan with IV contrast is strongly recommended due to higher rates of atypical presentations, complicated appendicitis, and mortality. 2

Management Algorithm Based on Imaging Results

CT Shows Uncomplicated Appendicitis

1. Administer broad-spectrum antibiotics immediately covering aerobic gram-negatives and anaerobes (e.g., piperacillin-tazobactam, or cephalosporin/fluoroquinolone plus metronidazole) 3, 4
2. Surgical consultation for appendectomy as soon as reasonably feasible (within 24 hours for uncomplicated cases) 3
3. Both laparoscopic and open approaches are acceptable; laparoscopic is preferred in children 3

CT Shows Complicated Appendicitis (Perforation, Abscess, Phlegmon)

Findings indicating complicated disease: extraluminal appendicolith, abscess, extraluminal air, appendiceal wall enhancement defect, periappendiceal fat stranding 2

1. Urgent surgical intervention for source control 3
2. Large periappendiceal abscess (>3 cm) may warrant percutaneous drainage rather than immediate appendectomy 3, 6
3. Early appendectomy within 8 hours is recommended for complicated cases 3

Imaging Negative but High Clinical Suspicion Persists

Consider observation with serial examinations, repeat imaging in 6-12 hours, or surgical consultation if clinical suspicion is very high. 2, 3

• Ensure 24-hour follow-up if discharged 2
• Do not assume negative imaging excludes appendicitis in high-risk patients 3

Special Considerations: Non-Operative Management

In highly selected patients with uncomplicated appendicitis and NO appendicolith on CT, an antibiotics-first strategy can be discussed as an alternative to surgery. 3, 4

Success Rates and Risk Factors for Failure

• Overall success rate: 63-73% at one year 3, 4
• High-risk CT findings predicting antibiotic failure (≈40% failure rate): 4
  • Appendicolith present
  • Appendiceal diameter >13 mm
  • Mass effect

Recommendation: Surgical management should be recommended in patients with these high-risk CT findings who are fit for surgery. 4 In unfit patients without high-risk findings, antibiotics-first is reasonable. 4

Common Pitfalls to Avoid

1. Do not administer analgesics before completing diagnostic evaluation—while pain control is important, premature analgesia can mask evolving peritoneal signs 7

2. Do not proceed directly to surgery based on incomplete clinical findings without imaging—this risks unnecessary surgery (negative appendectomy carries long-term morbidity) and missing alternative diagnoses 2

3. Do not delay antibiotics once appendicitis is confirmed or strongly suspected—this increases complication risk 3

4. Do not rely solely on clinical examination in elderly patients—atypical presentations are common and CT is essential 2

5. Ultrasound accuracy is highly operator-dependent—both ultrasound and MRI may incorrectly classify up to half of perforated appendicitis cases as simple appendicitis 2

6. Do not assume absence of peritoneal signs excludes appendicitis—especially in early presentations, children, elderly, and pregnant patients 3, 7