When the Appendix Is Not Seen on Ultrasound for Right Lower Quadrant Pain: Does the Interpretation of Emergency Department Physicians Correlate With Diagnostic Performance?

A survey was administered to 166 academic emergency department (ED) physicians to determine their interpretation and practice after receiving an ultrasound (US) report with nonvisualization of the appendix (NVA). Annual incidence of reported NVA from 2 academic hospitals was calculated for 2002-2013. A retrospective review of the same hospitals revealed that 291 (17.4%) of 1672 USs performed for appendicitis in 2012 indicated NVA. These cases underwent a chart review to determine the negative predictive value of reported NVA and utility of secondary findings. Univariate analysis was performed to determine significant predictors of secondary signs of appendicitis on computed tomography. Ninety eight (59%) of 166 ED physicians completed the survey. Forty nine (52%) of 94 respondents agreed that in the setting of reported NVA with no other acute findings, appendicitis has not been excluded and requires further imaging. There was a significant rise in the incidence rate of reported NVA for appendicitis, 22.5% (2002) up to 41.2% (2013, P < 0.0001). Negative predictive value for reported NVA was 216 (94.3%) of 229; in 9 (69%) of 13 patients, secondary signs of appendicitis were noted. Inflammatory changes in right lower quadrant (P = 0.01) and focal tenderness (P = 0.02) noted on US were significant predictors of a positive computed tomography scan. Current perceptions and practice of some ED physicians equate NVA on US as an inadequate study to exclude appendicitis. However, reported NVA is itself a highly predictive sign (94.3%) of absence of appendicitis even when an alternate cause of pain is not seen.