Table 2.
Diagnostic performance of individual ultrasound findings for appendicitis
| Ultrasound findings | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | Accuracy (%) |
|---|---|---|---|---|---|
| Appendix maximal diameter (7.9 mm)a | 37.0 (19.4, 57.6) | 90.9 (75.7, 98.1) | 76.9 (46.2, 95.0) | 63.8 (48.5, 77.3) | 66.7 (53.3, 78.3) |
| Appendix wall thickness (2 mm)sup>a | 37.0 (19.4, 57.6) | 84.8 (68.1, 94.9) | 66.7 (38.4, 88.2) | 62.2 (46.5, 76.2) | 63.3 (50.0, 75.4) |
| Appendix luminal diameter (4.5 mm)a | 37.0 (19.4, 57.6) | 90.9 (75.7, 98.1) | 76.9 (46.2, 95.0) | 63.8 (48.5, 77.3) | 66.7 (53.3, 78.3) |
| Increased wall flow in appendix | 55.6 (35.3, 74.5) | 90.9 (75.5, 98.1) | 83.3 (58.6, 96.4) | 71.4 (55.4, 84.3) | 63.3 (50.0, 75.4) |
| Appendix mucosal discontinuity | 25.9 (11.1, 46.3) | 100 (89.4, 100) | 100 (59.0, 100) | 62.3 (47.9, 75.2) | 66.7 (53.3, 78.3) |
| Non-compressibility of appendix | 85.2 (66.3, 95.8) | 60.6 (42.1, 77.1) | 63.9 (46.2, 79.2) | 83.3 (62.6, 95.3) | 71.7 (58.6, 82.5) |
| Probe tendernessover the appendix | 74.1 (53.7, 88.9) | 97.0 (84.2, 99.9) | 95.2 (76.2, 99.9) | 82.1 (66.5, 92.5) | 86.7 (75.4, 74.1) |
| Periappendiceal increased echo | 22.2 (8.6, 42.3) | 97.0 (84.2, 99.9) | 85.7 (42.1, 99.6) | 60.4 (46, 73.5) | 63.3 (50.0, 75.4) |
NPV, negative predictive value; PPV, positive predictive value.
Data in parentheses are the 95% confidence interval.
a
Data in parentheses are the optimal cut-off values of continuous variables for discrimination of appendicitis which were obtained by the receiver operating characteristic curve and Youden index.