What is the best course of action for a patient with suspected appendicitis or other serious abdominal conditions, who has stable vital signs and a normal leukocyte count?

Management of Suspected Appendicitis with Stable Vital Signs and Normal Leukocyte Count

Do not rule out appendicitis based solely on stable vital signs and a normal white blood cell count—proceed immediately with diagnostic imaging (CT with IV contrast in adults, ultrasound in children) because appendicitis can present with normal laboratory values in 11-30% of cases, and the severity of disease does not correlate with WBC elevation. 1, 2

Critical Evidence Against Relying on Clinical Stability

The absence of fever, stable vital signs, and normal WBC count do not exclude appendicitis and should never be used as sole criteria for discharge. The evidence is unequivocal:

• Fever is absent in approximately 50% of appendicitis cases 3
• Normal WBC count occurs in 11% of all appendicitis patients, with identical rates of gangrenous (13% vs 17%) and perforated appendicitis (29% vs 27%) compared to those with elevated WBC 2
• In elderly patients, 96% with appendicitis had either abnormal total or differential WBC, meaning 4% had completely normal counts even with confirmed appendicitis 4, 5
• Most critically: 22% of patients with normal WBC counts had diffuse peritonitis, the most severe form of appendicitis 2

Recommended Diagnostic Algorithm

Step 1: Risk Stratification Using Clinical Scores

Use validated clinical scoring systems (AIR score or AAS score) that combine symptoms, physical examination, AND laboratory values—never rely on labs alone. 6

• The Alvarado score has limited specificity and should not be used to confirm appendicitis in adults 6
• The AIR and AAS scores have the highest discriminating power and should guide your imaging decisions 6
• Even with low clinical scores, 8.4% of patients ultimately had appendicitis, and one study found 72% of patients with very low Alvarado scores (1-4) had confirmed appendicitis 3

Step 2: Proceed Directly to Imaging Based on Age

For adults (including elderly patients):

• Order CT abdomen and pelvis with IV contrast immediately—this is the gold standard with 96-100% sensitivity and 93-95% specificity 3, 7
• IV contrast increases sensitivity to 96% compared to unenhanced CT 7
• Oral contrast is unnecessary and delays diagnosis 3
• In elderly patients, CT is strongly recommended due to 25% complication rate with negative appendectomy (vs 3% in younger patients) and higher perforation rates 6

For children and adolescents:

• Start with ultrasound (sensitivity 76%, specificity 95%) to avoid radiation 3, 7
• If ultrasound is nondiagnostic or equivocal, proceed immediately to CT 3
• Staged ultrasound followed by CT achieves 99% sensitivity and 91% specificity 3

For pregnant patients:

• Ultrasound first, then MRI (not CT) if inconclusive—MRI has 94-96% sensitivity and specificity 3, 7

Step 3: Laboratory Testing Strategy

Order WBC with differential AND C-reactive protein, but interpret them correctly:

• The combination of elevated WBC (>10,000/mm³) AND left shift has a positive likelihood ratio of 9.8 8
• The combination of WBC >10,000/mm³ AND CRP ≥8 mg/L has a positive likelihood ratio of 23.32 and negative likelihood ratio of 0.03 7
• Neutrophil percentage >75% is the most sensitive individual marker (82% sensitivity) 1
• In elderly patients, if both WBC and CRP are normal, the negative predictive value is 100%—but this requires BOTH to be normal 6, 5

Critical Pitfalls to Avoid

Never discharge a patient with suspected appendicitis based on:

• Stable vital signs alone 1, 3
• Normal WBC count alone 1, 4, 2
• Absence of fever 3
• Clinical improvement after NSAIDs (which can mask evolving symptoms) 3

The complication rate in elderly patients with negative appendectomy is 25% vs 3% in younger patients, making accurate preoperative diagnosis essential. 6

Management After Imaging

If CT confirms appendicitis:

• Initiate broad-spectrum antibiotics immediately (covering gram-negative organisms and anaerobes) 6
• Proceed to appendectomy as urgent/emergent procedure 6
• For complicated appendicitis with abscess, consider percutaneous drainage in hemodynamically stable patients with major comorbidities 6

If imaging is negative but clinical suspicion remains:

• Admit for 24-hour observation with serial abdominal examinations every 6-12 hours 3
• Repeat WBC to monitor for leukocytosis trend 3
• If symptoms persist or worsen, repeat imaging 3

Never proceed directly to surgery without imaging in a patient with incomplete clinical findings and normal labs—this risks unnecessary surgery (negative appendectomy) and missing alternative diagnoses that CT identifies in 23-45% of cases. 3, 7