A systematic review including 32 studies with a total of 6 805 subjects was abstracted in DARE. Ultrasonography: All presentations (17 studies): the overall prevalence of appendicitis was 41% (range: 23 to 78). The sensitivity was 88.3 (95% CI: 86.7 to 89.8) and the specificity was 92.3 (95% CI: 91.2 to 93.3). Equivocal presentation only (5 studies): the overall prevalence of appendicitis was 28% (range: 19 to 54). The sensitivity was 76.4 (95% CI: 70.1 to 81.7) and the specificity was 95.2 (95% CI: 93.0 to 96.7). Computed tomography: All presentations (7 studies): the overall prevalence of appendicitis was 46% (range: 24 to 72). The sensitivity was 96.6 (95% CI: 94.3 to 98.0) and the specificity was 94.0 (95% CI: 91.6 to 95.8). Equivocal presentation only (5 studies): the overall prevalence of appendicitis was 46% (range: 30 to 78). The sensitivity was 96.4 (95% CI: 93.4 to 98.0) and the specificity was 95.7 (95% CI: 92.9 to 97.4).
A systematic review including 17 studies with a total of 3 358 of which 1 247 had appendicitis was abstracted in DARE. The pooled sensitivity of ultrasound was 84.7% (95% CI 81.0 to 87.8%) and specificity was 92.1% (95% CI 88.0 to 95.2%). In patients with clear clinical appendicitis the positive predictive value (PPV) was 97.6%, in patients with intermediate signs requiring serial observation the PPV was 87.3%, and in the group with a low probability of appendicitis usually released home the PPV was 19.8%. The negative predictive values for the three groups of patients were 59.5%, 89.9%, and 99.7%.
A systematic review including 57 studies was abstracted in DARE. Twenty-six studies of children (mean age 7 to 12 years) reported results for US alone (6,850 participants), CT alone (598 participants), or combined US and CT (1,908 participants). Thirty-one studies of adults (mean age 20 to 49 years) reported results for US alone (903 participants), CT alone (2,394 participants), or combined US and CT (1,044 participants). The pooled sensitivity of CT in children (94%, 95% CI: 92, 97) was 6% higher than that of US (88%, 95% CI: 86, 90) after the removal of one outlier (p=0.001). The pooled sensitivity of CT in adults (94%, 95% CI: 92, 95) was 11% higher than that of US (83%, 95% CI: 78, 87) after the removal of two outliers (p=0.001). The pooled estimates of specificity were similar for CT in children (95%, 95% CI: 94, 97) and in adults (94%, 95% CI: 94, 96), and for US in children (94%, 95% CI: 92, 95) and in adults (93%, 95% CI: 90, 96).
Comment: The quality of evidence is downgraded by poor reporting of the methodology of the included studies. The use of CT should be limited because of radiation, particularly in children. Orr et al. conclude that ultrasound should not be used to exclude appendicitis in patients with classic signs of the illness, but it can be used to indicate the necessity of operation or extended observation in patients with intermediate probability of the illness. Ultrasound is not recommended in patients with a low probability of appendicitis. Weston et al. do not recommend the routine use of CT. The CDR reviewers of Weston et al. study suggest that the high sensitivity and specificity of CT may be overstated.