From the Guidelines
The most effective scan for diagnosing appendicitis is a CT (computed tomography) scan with contrast, as it has high diagnostic yield and sensitivity, ranging from 85.7% to 100%, and specificity, ranging from 94.8% to 100% 1. When it comes to diagnosing appendicitis, imaging tests play a crucial role in confirming inflammation, ruling out other conditions with similar symptoms, and guiding treatment decisions.
- The use of CT scans for diagnosing appendicitis has increased over the years, with a study showing an increase from 7.2% to 83.3% between 1997 and 2016 1.
- CT scans with contrast have been shown to have high sensitivity and specificity, with values ranging from 90% to 100% and 94.8% to 100%, respectively 1.
- The signs of appendicitis on CT scans, such as maximal outer diameter, fat stranding, and absence of intraluminal gas, have variable accuracy, but the presence of two or more signs can increase the odds ratio of appendicitis being present 1.
- A meta-analysis of 71 study populations found a summary sensitivity of 0.95 and a summary specificity of 0.94 for CT in the diagnosis of appendicitis 1.
- The study also found that contrast-enhanced CT without enteral contrast had a sensitivity of 100% and a specificity of 99.5% in a subgroup analysis of 113 patients with appendicitis 1.
- While other imaging tests, such as abdominal ultrasound and MRI, can be used, particularly in certain patient populations, CT scans with contrast remain the most effective and commonly used test for diagnosing appendicitis 1.
From the Research
Diagnosis of Appendicitis using CT Scan
- The use of computed tomography (CT) scans in diagnosing appendicitis has been extensively studied, with research indicating high sensitivity and specificity rates 2, 3, 4, 5.
- A study published in 2019 found that the summary sensitivity of CT scans for diagnosing appendicitis was 0.95, while the summary specificity was 0.94 2.
- Another study from 2014 noted that low-dose unenhanced CT is equal to standard-dose CT with intravenous contrast agents in detecting signs of acute appendicitis 3.
Comparison of CT Scan Techniques
- Research has compared the accuracy of nonenhanced CT (NECT) and contrast-enhanced CT (CECT) for diagnosing acute appendicitis, with one study finding no significant difference between the two techniques 4.
- A 2021 study found that the sensitivity, specificity, and accuracy of NECT, CECT, and NECT + CECT for diagnosing acute appendicitis were similar, with no significant difference between the three techniques 4.
- The use of at least 3 imaging findings for NECT or at least 4 for CECT was found to have the best diagnostic accuracy 4.
Role of CT Scan in Clinically-Suspected but Equivocal Acute Appendicitis
- A 2004 study found that contrast-enhanced CT of the abdomen and pelvis was a safe, reliable, and accurate modality in diagnosing acute appendicitis in patients with equivocal presentation, with a sensitivity of 93.9%, specificity of 100%, and accuracy of 98.5% 5.
- Another study from 2015 noted that dedicated appendiceal USG should be used as a primary imaging modality in diagnosing or excluding acute appendicitis, with appendiceal CT serving as a problem-solving modality 6.