Some consider nonvisualization of the appendix as an equivocal result [40,61]. However, in several retrospective studies, an appendiceal US in which the appendix is not visualized and no inflammatory findings are present in the RLQ has high negative predictive value [3,62-64]. In this context, further imaging is unlikely to be contributory unless there is discordance between the clinical picture and the negative US result [65]. Further imaging, however, is contributory after equivocal US examinations in which the appendix is either visualized or not visualized, and there are findings that could reflect appendicitis. In one study, appendicitis was present in 26% of patients who met this criteria [3]. While there is good evidence regarding secondary imaging modalities following an equivocal US, there is also evidence of the benefit of repeat clinical assessment in these cases, which can obviate further imaging at the expense of delay in diagnosis and the risk associated with extending the hospital visit [10,66]. Schuh et al [67] in a prospective study found that of 123 patients with an initially equivocal US, acute appendicitis could be correctly ruled out clinically in 59% based on reassessment without further imaging. Radiography Abdomen Given the limited sensitivity and specificity, a radiograph is unlikely to diagnose acute appendicitis in patients with an initial equivocal or nondiagnostic appendiceal US [51]. Radiographs may identify an alternative cause of pain. US Abdomen RLQ Repeating a US examination after an initially equivocal result increases sensitivity for acute appendicitis. Schuh et al [67] showed that repeat US could make a diagnosis in 55% of cases with persistent clinical concern for acute appendicitis after an initially equivocal US. This final diagnosis rate, however, is lower than what has been reported with both CT and MRI.
Suspected Appendicitis Child. Some consider nonvisualization of the appendix as an equivocal result [40,61]. However, in several retrospective studies, an appendiceal US in which the appendix is not visualized and no inflammatory findings are present in the RLQ has high negative predictive value [3,62-64]. In this context, further imaging is unlikely to be contributory unless there is discordance between the clinical picture and the negative US result [65]. Further imaging, however, is contributory after equivocal US examinations in which the appendix is either visualized or not visualized, and there are findings that could reflect appendicitis. In one study, appendicitis was present in 26% of patients who met this criteria [3]. While there is good evidence regarding secondary imaging modalities following an equivocal US, there is also evidence of the benefit of repeat clinical assessment in these cases, which can obviate further imaging at the expense of delay in diagnosis and the risk associated with extending the hospital visit [10,66]. Schuh et al [67] in a prospective study found that of 123 patients with an initially equivocal US, acute appendicitis could be correctly ruled out clinically in 59% based on reassessment without further imaging. Radiography Abdomen Given the limited sensitivity and specificity, a radiograph is unlikely to diagnose acute appendicitis in patients with an initial equivocal or nondiagnostic appendiceal US [51]. Radiographs may identify an alternative cause of pain. US Abdomen RLQ Repeating a US examination after an initially equivocal result increases sensitivity for acute appendicitis. Schuh et al [67] showed that repeat US could make a diagnosis in 55% of cases with persistent clinical concern for acute appendicitis after an initially equivocal US. This final diagnosis rate, however, is lower than what has been reported with both CT and MRI.