What is the appropriate initial test for suspected appendicitis (inflammation of the appendix)?

From the Guidelines

The most appropriate initial test for suspected appendicitis is Point-of-Care Ultrasound (POCUS), as it is a reliable and satisfactory diagnostic tool with good sensitivity and specificity, according to the 2020 update of the WSES Jerusalem guidelines 1. When it comes to diagnosing acute appendicitis, a thorough clinical assessment is crucial, and imaging investigations should be indicated based on this assessment.

• The use of POCUS as the first-line diagnostic tool is recommended in both adults and children, with a moderate quality of evidence and a weak strength of recommendation [QoE: Moderate; Strength of recommendation: Weak; 2B] [1].
• In patients with normal investigations and symptoms unlikely to be acute appendicitis but which do not settle, cross-sectional imaging is recommended before surgery, highlighting the importance of a comprehensive diagnostic approach 1.
• For pediatric patients with suspected appendicitis, the use of ultrasound as first-line imaging is suggested, given its accuracy and safety in terms of perforation rates, emergency department re-visits, and negative appendectomy rates 1. Key considerations in the diagnostic process include:
• Clinical evaluation, including history and physical examination focusing on right lower quadrant tenderness
• Laboratory tests, such as complete blood count and C-reactive protein, which can support the diagnosis but are not definitive on their own
• The potential need for further imaging, such as contrast-enhanced low-dose CT scan, if POCUS results are inconclusive and clinical suspicion remains high, particularly in adolescents and young adults with suspected acute appendicitis and negative US findings [QoE: High; Strength of recommendation: Strong; 1A] [1].

From the Research

Initial Testing for Suspected Appendicitis

The appropriate initial test for suspected appendicitis is a topic of discussion among medical professionals.

• Transabdominal ultrasound should be the first-line imaging test for suspected appendicitis, especially in pediatric and young adult populations, as well as in pregnant patients 2, 3, 4.
• Ultrasound (US) is the basic diagnostic method in case of suspected appendicitis, and it is recommended as the first line imaging modality for all ages, particularly for children and non-obese young adults including women of reproductive age group 2, 3.
• Bedside ultrasound (BUS) may be an appropriate initial test to evaluate patients with suspected acute appendicitis in the emergency department, with a sensitivity of 67.65% and a specificity of 98.41% 5.

Special Considerations

• In patients with atypical clinical presentation of appendicitis and suspected perforation, abdominal CT is superior to US and is required immediately 2.
• MRI should be the first-line imaging test in pregnant women, and it is also necessary in pediatric and pregnant patients with inconclusive initial USG findings 2, 6, 3.
• Routine use of CT scan for diagnosis of appendicitis needs to be discouraged, unless it is necessary in patients with atypical presentation of appendicitis or suspected perforation 3.

Imaging Modalities

• Three imaging modalities are available for the diagnosis of acute appendicitis: ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) 2, 6, 4.
• MRI appears to be highly accurate in confirming and excluding acute appendicitis in adults, children, and pregnant women, with a summary sensitivity of 0.95 and a summary specificity of 0.96 6.