What is the appropriate workup and treatment for a patient suspected of having appendicitis?

Workup for Suspected Appendicitis

Use a risk-stratified approach combining clinical scoring systems with tailored imaging—AIR or AAS scores for adults, ultrasound first for children and pregnant patients, and CT with IV contrast for non-pregnant adults with intermediate-to-high clinical suspicion. 1, 2

Initial Clinical Assessment

Risk Stratification with Clinical Scores

Apply the AIR (Appendicitis Inflammatory Response) score or AAS (Adult Appendicitis Score) in adults—these are the best-performing clinical prediction tools with the highest discriminating power. 1

• These scores effectively identify low-risk patients who can avoid imaging and hospital admission, while flagging intermediate-risk patients who need diagnostic imaging 1
• The Alvarado score should NOT be used alone to confirm appendicitis in adults due to insufficient specificity, though it helps exclude the diagnosis 1
• In pediatric patients, use the Alvarado or Pediatric Appendicitis Score to exclude appendicitis, but never make the diagnosis based on clinical scores alone 1

Key Clinical Findings to Assess

• Positive predictors: Psoas sign, fever, migratory pain from periumbilical region to right lower quadrant, rebound tenderness, guarding, and rigidity 2, 3
• Negative predictor: Vomiting occurring before pain onset makes appendicitis less likely 2
• In children specifically: absent/decreased bowel sounds, positive psoas sign, positive obturator sign, positive Rovsing sign, difficulty walking, and focal right lower quadrant pain 2, 3

Laboratory Testing

• Obtain WBC with differential and CRP in all patients 1
• The combination of WBC >10,000/mm³ AND CRP ≥8 mg/L has the strongest predictive value (positive likelihood ratio 23.32) 2
• In children, WBC ≥10,100/mm³ combined with fever >38°C and rebound tenderness creates a prediction rule with only 1% missed appendicitis rate 2
• In pediatric patients, CRP ≥10 mg/L and leukocytosis ≥16,000/mL are strong predictive factors 1

Imaging Strategy Based on Risk Stratification

Low-Risk Patients (Low Clinical Scores)

• Consider discharge with 24-hour follow-up and minimal or no imaging 2, 4
• Critical pitfall: Even low Alvarado scores don't reliably exclude appendicitis—8.4% of patients with appendicitis had scores below 5 in some studies 2

Intermediate-Risk Patients

Proceed with systematic diagnostic imaging based on patient population 1:

Non-Pregnant Adults

• CT abdomen/pelvis with IV contrast is the primary imaging modality with sensitivity 96-100% and specificity 93-95% 1, 2, 4
• IV contrast is essential—it increases sensitivity to 96% compared to unenhanced CT 2
• Oral contrast is NOT necessary and may delay diagnosis 2
• Consider low-dose CT with contrast in adolescents and young adults to reduce radiation exposure 1

Children and Adolescents

• Ultrasound is the first-line imaging modality with sensitivity 76% and specificity 95% 2, 4
• Point-of-care ultrasound (POCUS) performed by emergency physicians or surgeons shows even higher accuracy (sensitivity 91%, specificity 97%) 1, 2
• Key ultrasound findings: appendiceal diameter ≥7 mm, non-compressibility, appendiceal tenderness 2
• If ultrasound is non-diagnostic and clinical suspicion persists, proceed to MRI or CT 2

Pregnant Patients

• Ultrasound with graded compression is the initial imaging modality 2, 4
• If ultrasound is inconclusive, use MRI without IV contrast (sensitivity 94%, specificity 96%) rather than CT to avoid radiation 1, 2, 4
• Peritoneal signs may be less reliable due to anatomic displacement 2

Elderly Patients

• CT scan with IV contrast is strongly recommended due to higher rates of complicated appendicitis, atypical presentations, and increased mortality in this population 2

High-Risk Patients (High Clinical Scores)

• Patients under 40 years with very high scores (AIR 9-12, Alvarado 9-10, AAS ≥16) may proceed directly to surgical consultation without pre-operative imaging 1
• However, imaging is still recommended in most cases to confirm diagnosis, assess for complications, and reduce negative appendectomy rates 1, 2

Combined Clinico-Radiological Approach

Combine ultrasound findings with clinical scores to significantly improve diagnostic accuracy and reduce the need for CT 1:

• This integrated approach is particularly effective in reducing radiation exposure while maintaining diagnostic accuracy 1
• Use POCUS as the most appropriate first-line diagnostic tool when imaging is indicated based on clinical assessment 1

Management After Imaging

If Imaging Confirms Appendicitis

• Administer broad-spectrum antibiotics immediately covering aerobic gram-negative organisms and anaerobes 4, 5
• Arrange urgent surgical consultation for appendectomy (laparoscopic preferred in children) 4
• Surgery should be performed within 24 hours for uncomplicated appendicitis, within 8 hours for complicated appendicitis 4

If Imaging Shows Complicated Appendicitis

• CT findings suggesting perforation/complication: extraluminal appendicolith, abscess, extraluminal air, appendiceal wall enhancement defect, periappendiceal fat stranding 2
• Large periappendiceal abscess may warrant percutaneous drainage rather than immediate appendectomy 4

If Imaging is Negative but Clinical Suspicion Remains

• Ensure 24-hour follow-up due to risk of false-negative results 6, 4
• Consider observation with supportive care, with or without antibiotics 2
• If index of suspicion remains very high, possible hospitalization for serial examinations 6

Critical Pitfalls to Avoid

• Never rely on clinical scores alone to confirm appendicitis—they are best for exclusion and risk stratification 1
• Ultrasound accuracy is highly operator-dependent, and both ultrasound and MRI may incorrectly classify up to half of perforated appendicitis cases as simple appendicitis 2
• Don't skip imaging in female patients of childbearing age—obtain pregnancy test first, then proceed with appropriate imaging 4
• Don't delay antibiotics once diagnosis is established or strongly suspected—this increases complication risk 4
• Don't proceed directly to surgery without imaging in patients with incomplete clinical findings—this risks unnecessary surgery (negative appendectomy carries long-term morbidity) and missing alternative diagnoses 2
• Don't forget 24-hour follow-up for discharged patients with negative imaging but persistent symptoms 6, 4