Acute appendicitis in childhood: oral contrast does not improve CT diagnosis.

Introduction: We compared the diagnostic accuracy of CT performed without and with oral contrast for suspected appendicitis in children.

Methods: In this retrospective cohort study, we reviewed abdomen/pelvis CT scans with IV contrast performed between 2011 and 2015 for suspected appendicitis. Oral contrast was used routinely before August 2013 and eliminated from the CT protocol thereafter. Diagnostic accuracy of CT was compared with operative/pathology reports, and included a 30-day follow-up period for non-surgical patients. For a secondary analysis, the oral contrast group was subdivided into "complete" (contrast extending into the cecum) or "partial" contrast. We also compared groups for CT turnaround time, the frequency of appendiceal perforation and abscess, and the potential influence of a prior appendix ultrasound.

Results: Five hundred fifty-eight patients were included: 51.6% (n = 288) without oral contrast and 48.4% (n = 270) with oral contrast (of which 52% (n = 140/270) had "complete" contrast). There was no difference in diagnostic accuracy between the oral contrast and non-contrast groups (p = 0.903), with sensitivity/specificity of 93.8% (95% CI 84.8-98.3)/98.5% (CI 95.8-99.7) and 94.6% (CI 84.9-98.9)/98.3% (CI 95.7-99.5), respectively. Similarly, there was no difference in accuracy when comparing only "complete" contrast vs. non-contrast groups (p = 0.755). CT turnaround time for the non-contrast group was significantly faster (43.8 ± 37.6 min), on average, than the oral contrast group (137.4 ± 47.5 min).

Conclusion: For children evaluated by CT with IV contrast for suspected appendicitis, administering oral contrast increased wait time by > 90 min, did not reach the cecum in 48% of cases, and did not improve diagnostic accuracy. Oral contrast for pediatric CT appendicitis evaluation is not warranted.