From the Guidelines
Computed Tomography (CT) with intravenous contrast is the best imaging study to rule out appendiceal rupture. When appendiceal rupture is suspected, a contrast-enhanced CT scan of the abdomen and pelvis should be performed promptly as it offers superior sensitivity (94-98%) and specificity (95-97%) for detecting both appendicitis and complications like perforation 1. The CT findings suggestive of rupture include periappendiceal fluid, abscess formation, extraluminal air, phlegmon, or appendicolith outside the appendix.
Key Considerations
- The use of CT for adult emergency department visits for diagnosis of appendicitis has increased significantly, with a summary sensitivity of 0.95 (95% CI: 0.93-0.96) and a summary specificity of 0.94 (95% CI: 0.92-0.95) for CT in the diagnosis of appendicitis 1.
- Contrast-enhanced CT without enteral contrast has been shown to have a sensitivity of 100% and a specificity of 99.5% in a subgroup analysis of 113 patients with appendicitis 1.
- CT signs of appendicitis, such as maximal outer diameter >6 mm, fat stranding, and absence of intraluminal gas, have variable accuracy, but the presence of two or more signs can increase the odds of appendicitis being present 1.
Alternative Imaging Modalities
- Ultrasound may be used as an initial imaging modality, particularly in children and pregnant women to avoid radiation exposure, but it is less reliable for detecting perforation with sensitivity around 86% 1.
- MRI is an alternative for pregnant patients or those who cannot receive CT contrast, though it's less readily available and takes longer to perform 1.
Management Decisions
- The advantage of CT lies in its ability to visualize the entire abdomen, identify alternative diagnoses, and guide management decisions, especially when surgical intervention is being considered for suspected appendiceal rupture 1.
- CT findings can help identify early signs of appendiceal necrosis and occult perforation, which is crucial for reducing morbidity, mortality, and length of stay 1.
From the Research
Imaging Modalities for Diagnosing Appendicitis
The following imaging modalities are available for diagnosing appendicitis:
- Ultrasound (US)
- Computed Tomography (CT)
- Magnetic Resonance Imaging (MRI)
Best Imaging Study to Rule Out Appendiceal Rupture
According to the studies, CT scan is the most effective imaging modality for diagnosing appendicitis and ruling out appendiceal rupture 2, 3, 4.
- Abdominal CT is superior to US and is required immediately in patients with atypical clinical presentation of appendicitis and suspected perforation 2.
- CT scan can accurately determine appendiceal rupture in acute appendicitis and can further demonstrate the presence of local inflammatory mass, facilitating management decision in the emergency department (ED) 3.
- The sensitivity and specificity of CT for diagnosing appendicitis in adults are high, with summary sensitivity of 0.95 and summary specificity of 0.94 4.
CT Scan Findings for Appendiceal Rupture
The following CT scan findings are significant for predicting appendiceal rupture:
- Abscess
- Extraluminal air
- Wall defect
- Peritoneal enhancement
- Extraluminal appendolith
- Phlegmon
- Localized fluid
- Fascial thickening
- Ascites
- Stool impaction
- Bowel wall thickening 3
Other Imaging Modalities
While US is the basic diagnostic method in case of suspected appendicitis, it may not be as effective as CT in diagnosing appendicitis and ruling out appendiceal rupture 2, 5.