From the Guidelines
To rule out appendicitis, a step-up approach for diagnosis should be used, beginning with clinical and laboratory examination and progressing to imaging examinations, with CT scan being the most accurate imaging method for adults, as recommended by the World Journal of Emergency Surgery 1.
Diagnosis of Appendicitis
The diagnosis of appendicitis is mainly clinical, and early detection and treatment are essential to minimize complications. Patients with appendicitis typically present with rapid-onset abdominal pain and signs of local and systemic inflammation.
- The presence of a positive psoas sign, fever, or migratory pain to the right lower quadrant suggests an increased likelihood of appendicitis.
- Conversely, the presence of vomiting before pain makes appendicitis unlikely 1.
Imaging Studies
Imaging studies are crucial for diagnosis, with the following options:
- Ultrasound (US) is often used as the first-line imaging test, particularly in children and pregnant women, due to its lack of radiation.
- CT scan with contrast is the most accurate imaging method for adults, with sensitivity and specificity exceeding 95% 1.
- MRI may be used for pregnant patients when ultrasound is inconclusive.
Clinical Scoring Systems
The Alvarado score, which combines symptoms, signs, and laboratory findings, can help stratify the risk of appendicitis.
- A score below 4 makes appendicitis unlikely.
Observation and Serial Examinations
If appendicitis is still suspected despite negative initial tests, observation with serial examinations may be necessary, as the clinical presentation can evolve over time.
- Only a healthcare professional can definitively rule out appendicitis, so anyone with persistent abdominal pain, especially in the right lower quadrant, should seek medical attention promptly 1.
From the Research
Ruling Out Appendicitis
To rule out appendicitis, several methods can be employed, including:
- Clinical evaluation: Assessing symptoms such as vague periumbilical pain, anorexia/nausea/intermittent vomiting, migration of pain to the right lower quadrant, and low-grade fever 2
- Laboratory tests: Evaluating white blood cell count, C-reactive protein (CRP), and other biomarkers 3, 4
- Imaging studies: Utilizing ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) to visualize the appendix and surrounding tissues 5, 3, 4, 6
Clinical Decision Rules
Clinical decision rules can be used to rule out appendicitis in patients with nondiagnostic ultrasound results. For example:
- A rule that selects patients for discharge and next-day reevaluation without initial CT or MRI if fewer than two of the following predictors are present: male sex, migration of pain to the right lower quadrant, vomiting, and white blood cell count higher than 12.0 × 10(9) /L 5
- The Pediatric Appendicitis Score (PAS) can also be used to evaluate the likelihood of appendicitis in pediatric patients 6
Imaging Modalities
Different imaging modalities have varying degrees of sensitivity and specificity for diagnosing appendicitis:
- Ultrasound (US): Sensitivity and specificity of 74.8% and 62.5%, respectively 3
- Computed Tomography (CT): Sensitivity and specificity of 99.4% and 80.0%, respectively 3
- Point-of-care Ultrasound (POCUS): Positive likelihood ratio of 9.24 and negative likelihood ratio of 0.17 6
Diagnostic Approach
A diagnostic approach that combines clinical evaluation, laboratory tests, and imaging studies can be used to rule out appendicitis: