Outcomes for Children With a Nonvisualized Appendix on Ultrasound

Oftentimes while pursing the diagnosis of appendicitis, an ultrasound cannot visualize the appendix, and physicians must utilize other resources for evaluation. The primary objective of this study was to determine if there was a lower rate of appendicitis when the appendix was not visualized on ultrasound. Furthermore, we assessed the importance of specific clinical predictors in this population.

We conducted a retrospective chart review of all children who presented to our pediatric emergency department from 2011 to 2013 and had an abdominal ultrasound. We identified total numbers of ultrasounds with a nonvisualized appendix and then assessed follow-up for a randomly selected group of patients. We performed logistic regression to assess the predictive value of different clinical factors.

A total of 3245 ultrasounds were analyzed, and in 54% of these, the appendix was nonvisualized. In total, 28% of the total patients and 11.9% of patients who received a nonvisualized ultrasound had appendicitis (95% confidence interval [CI], 8.3%-16.2%). Among those patients who had follow-up studies performed during the same visit, 21.2% had appendicitis (95% CI, 14.9%-28.8%), and of those discharged without a diagnosis, 1.5% had appendicitis (95% CI, 0.2%-5.4%). Male sex, leukocytosis, and an elevated absolute neutrophil count were each significantly associated with appendicitis after a nonvisualized appendix on ultrasound.

A significant proportion of patients with suspected appendicitis who had an initial nonvisualized appendix on ultrasound were ultimately diagnosed with appendicitis. Clinicians must be vigilant about pursuing a definitive diagnosis if an initial ultrasound is nondiagnostic.