Skip to main content

Table 4 Pre- and post-test probabilities of appendicitis, patients who underwent US or CT

From: Performance of imaging studies in patients with suspected appendicitis after stratification with adult appendicitis score

Probability of AA according to AAS

Pre-test probability of AA

Post-test probability of AA, positive test

Post-test probability of AA, negative test

US

 All patients, n = 497

177/497 (37%)

86/104 (83%)

91/393 (23%)

 High, n = 52

41/52 (75%)

19/20 (95%)

22/32 (69%)

 Intermediate, n = 258

122/258 (47%)

59/65 (91%)

63/193 (33%)

 Low, n = 187

17/187 (9%)

8/19 (42%)

9/168 (5.4%)

CT

 All patients, n = 489

257/489 (53%)

253/260 (97%)

4/229 (1.8%)

 High, n = 114

90/114 (79%)

90/91 (99%)

0/23 (0%)

 Intermediate, n = 276

138/276 (50%)

135/148 (91%)

3/128 (2.3%)

 Low, n = 99

16/99 (16%)

15/20 (75%)

1/79 (1.3%)

  1. AA, Acute appendicitis, AAS, Adult Appendicitis Score