The effect of point-of-care ultrasonography on emergency department length of stay and computed tomography utilization in children with suspected appendicitis

Abstract

Objectives: The role of clinician-performed ultrasonography (US) for suspected appendicitis is unclear. Published data conclude that US has high specificity to rule in the diagnosis of appendicitis, with variable sensitivity to rule it out. Newer data suggest that point-of-care (POC) US may have similar test characteristics. Our objective was to evaluate the effect of POC US in children with suspected appendicitis and its effect on emergency department (ED) length of stay (LOS) and computed tomography (CT) utilization.

Methods: This was a prospective observational convenience sample of children with suspected appendicitis requiring imaging evaluation that adhered to the Standards for the Reporting of Diagnostic accuracy studies (STARD) criteria. Outcomes were determined by operative or pathology report in those who had appendicitis, and 3-week phone follow-up in those patients who were nonoperative. Differences in ED LOS were analyzed by one-way analysis of variance (ANOVA) between patients who received dispositions after POC US, radiology US, or CT. Test performance characteristics were calculated for all imaging modalities.

Results: Among 150 enrolled patients, 50 had appendicitis (33.3%). There were no missed cases of appendicitis in discharged patients at 3-week phone follow-up, nor negative laparotomies in those who went to the operating room. Those who had dispositions after POC US (n = 25) had a significantly decreased mean ED LOS (154 minutes, 95% confidence interval [CI] = 115 to 193 minutes) compared with those requiring radiology US (288 minutes, 95% CI = 257 to 319 minutes) or CT scan (487 minutes; 95% CI = 434 to 540 minutes). Baseline CT rate was 44.2% (95% CI = 30.7% to 57.7%) prior to study start and decreased to 27.3% (95% CI = 20.17% to 34.43%) during the study. CTs were avoided in four patients with conclusive POC US results and inconclusive radiology US results. The sensitivity, specificity, positive likelihood ratio (LR+), and negative likelihood ratio (LR-) for POC US were 60% (95% CI = 46% to 72%), 94% (95% CI = 88% to 97%), 10 (95% CI = 4 to 23), and 0.4 (95% CI = 0.3 to 0.6). For radiology US they were 63% (95% CI = 48% to 75%), 99% (95% CI = 94% to 99%), 94 (95% CI = 6 to 1,500), and 0.4 (95% CI = 0.3 to 0.6); and for CT they were 83% (95% CI = 58% to 95%), 98% (95% CI = 85% to 99%), 45 (95% CI = 3 to 707), and 0.2 (95% CI = 0.05 to 0.5).

Conclusions: It may be feasible to reduce ED LOS and avoid CT scan when using POC US to evaluate children with suspected appendicitis. Test characteristics for POC US have high specificity to rule in appendicitis, similar to radiology US. Addition of POC US prior to sequential radiology imaging was safe, without missed cases of appendicitis or negative laparotomies.

© 2014 by the Society for Academic Emergency Medicine.