What is the management approach for a patient with suspected appendicitis, presenting with abdominal pain, fever, nausea, and vomiting?

Management of Suspected Appendicitis

Immediate Actions and Risk Stratification

For adults presenting with abdominal pain, fever, nausea, and vomiting concerning for appendicitis, immediately obtain CT abdomen and pelvis with IV contrast as the primary diagnostic test while simultaneously initiating risk stratification using validated clinical scoring systems. 1

Initial Clinical Assessment

• Apply the AIR (Appendicitis Inflammatory Response) score or AAS (Adult Appendicitis Score) to stratify patients into low, intermediate, or high-risk categories—these are the best-performing clinical prediction tools with the highest discriminating power 1, 2
• Do NOT use the Alvarado score alone to confirm appendicitis in adults due to insufficient specificity, though it helps exclude the diagnosis 1
• Obtain WBC with differential and CRP immediately—the combination of WBC >10,000/mm³ AND CRP ≥8 mg/L has a positive likelihood ratio of 23.32 for appendicitis 1, 3

Key Clinical Findings to Document

• Positive psoas sign, fever, or migratory pain to the right lower quadrant significantly increases likelihood of appendicitis 1, 4
• Rebound tenderness and guarding indicate peritoneal irritation and predict appendicitis across age groups 1, 2
• Vomiting before pain onset makes appendicitis less likely 1, 4
• The combination of guarding, fever >38°C, and WBC ≥10,100/mm³ creates a prediction rule with only 1% missed appendicitis rate 1

Imaging Strategy

Primary Imaging for Adults

CT abdomen and pelvis with IV contrast achieves sensitivity of 96-100% and specificity of 93-95% and is the definitive imaging modality for non-pregnant adults. 1, 3

• IV contrast alone is sufficient and strongly preferred—oral contrast is unnecessary and delays diagnosis 1, 3
• CT reduces negative appendectomy rates from historical 14.7% to current 1.7-7.7% 1
• CT findings of appendiceal diameter ≥7 mm, extraluminal appendicolith, abscess, extraluminal air, appendiceal wall enhancement defect, or periappendiceal fat stranding suggest complicated appendicitis 1, 5

Special Population Considerations

• Children and adolescents: Ultrasound is first-line imaging (sensitivity 76%, specificity 95%) to avoid radiation exposure; if inconclusive, proceed to MRI or CT 1, 3
• Pregnant patients: Ultrasound first-line; if inconclusive, MRI without IV contrast (sensitivity 94%, specificity 96%) is preferred over CT 1, 3
• Elderly patients: CT with IV contrast is strongly recommended due to higher rates of complicated appendicitis and mortality 1

Definitive Management

Antibiotic Therapy

Initiate broad-spectrum antibiotics immediately once appendicitis is diagnosed or strongly suspected, covering aerobic gram-negative organisms and anaerobes. 1, 3

• Recommended regimens include piperacillin-tazobactam monotherapy or combination therapy with cephalosporins or fluoroquinolones plus metronidazole 5
• Antibiotics should be started even before surgical intervention is arranged 3

Surgical Management

Appendectomy should be performed as soon as reasonably feasible once diagnosis is established—both laparoscopic and open approaches are acceptable, with laparoscopic preferred in children. 1, 3

• Immediate surgical consultation is required for patients with rigidity, as this indicates established peritonitis requiring source control 1
• For large periappendiceal abscess or phlegmon, percutaneous drainage combined with antibiotics may be warranted rather than immediate appendectomy 1, 3

Antibiotics-First Strategy (Selected Patients Only)

• In highly selected patients with uncomplicated appendicitis and absence of appendicolith on imaging, an antibiotics-first strategy can be discussed as an alternative to surgery with success rates of 63-73% at one year 1, 5
• Do NOT use antibiotics-first approach if CT shows appendicolith, mass effect, or dilated appendix >13 mm—these findings are associated with 40% treatment failure rates 5
• Pregnant patients and immunosuppressed patients should undergo timely surgical intervention to decrease risk of complications 6

Management Based on Risk Stratification

High Clinical Suspicion (High AIR/AAS Score)

• Refer directly to surgeon with minimal or no testing 1
• Proceed to appendectomy once diagnosis confirmed on CT 1

Intermediate Clinical Suspicion

• Obtain CT abdomen/pelvis with IV contrast 1, 3
• If CT confirms appendicitis, proceed to surgery and antibiotics 1
• If CT shows complicated appendicitis, urgent surgical intervention required 1

Low Clinical Suspicion

• Discharge with minimal or no testing and ensure 24-hour follow-up 1
• Consider alternative diagnoses 1

Critical Pitfalls to Avoid

• Never proceed directly to appendectomy without imaging in patients with incomplete clinical findings—this risks unnecessary surgery if appendicitis is absent (negative appendectomy carries long-term morbidity) and misses alternative diagnoses 1
• Low or incomplete Alvarado scores do not reliably exclude appendicitis—studies show 8.4% of patients with appendicitis had Alvarado scores below 5, and one study found 72% of patients with very low scores (1-4) ultimately had appendicitis 1
• Ultrasound accuracy is highly operator-dependent, and both MRI and ultrasound may incorrectly classify up to half of patients with perforated appendicitis as having simple appendicitis 1
• Atypical presentations are common in elderly patients, pregnant women, children, and patients with retrocecal or pelvic appendix position 2, 7

Follow-Up for Equivocal Cases

• If imaging is negative but clinical suspicion remains high, consider observation with or without antibiotics, or surgical intervention if clinical suspicion is very high despite negative imaging 1
• Follow-up within 24 hours if discharged due to low but measurable false-negative rates 1, 3
• Repeat CT or ultrasound imaging for patients not responding to initial treatment after 4-7 days 3