Influence of symptom duration and WBC profile on the negative predictive value of a nondiagnostic ultrasound in children with suspected appendicitis

BACKGROUND

The aim of this study was to explore the combined negative predictive value (NPV) of symptom duration and WBC profile in children with a nondiagnostic ultrasound (US) for appendicitis.

METHODS

This was a retrospective analysis of children with suspected appendicitis at a single children's hospital from 1/2010 to 3/2018. NPVs based on WBC profile and symptom duration at presentation were calculated individually and combined for children with a nondiagnostic US.

RESULTS

2277 patients were included, of which 1018 (44.7%) had a nondiagnostic US. The NPV of a nondiagnostic US ranged from 83.7% with ≤24 h of symptoms to 94.5% with >72 h of symptoms (p < 0.01). NPV also differed significantly across WBC profiles, ranging from 76.8% when WBC profile was elevated to 97.3% to when WBC profile was normal (p < 0.01). The range of NPVs for a nondiagnostic US was even greater when combining symptom duration and WBC profile, ranging from 73.7% for patients with 24-48 h of symptoms and an elevated WBC profile to 100% for patients with >72 h of symptoms and a normal WBC profile.

CONCLUSIONS

Incorporation of symptom duration and WBC profile significantly improves the accuracy and clinical utility of the negative predictive value associated with a nondiagnostic ultrasound.

LEVEL OF EVIDENCE

Study of diagnostic test level II: development of diagnostic criteria in a consecutive series of patients and a universally applied gold standard.

Improving ultrasound for appendicitis through standardized reporting of secondary signs

OBJECTIVE

Our aim was to implement a standardized US report that included secondary signs of appendicitis (SS) to facilitate accurate diagnosis of appendicitis and decrease the use of computed tomography (CT) and admissions for observation.

METHODS

A multidisciplinary team implemented a quality improvement (QI) intervention in the form of a standardized US report and provided stakeholders with monthly feedback. Outcomes including report compliance, CT use, and observation admissions were compared pretemplate and posttemplate.

RESULTS

We identified 387 patients in the pretemplate period and 483 patients in the posttemplate period. In the posttemplate period, the reporting of SS increased from 5.4% to 79.5% (p<0.001). Despite lower rates of appendix visualization (43.9% to 32.7%, p<0.001) with US, overall CT use (8.5% vs 7.0%, p=0.41) and the negative appendectomy rate remained stable (1.0% vs 1.0%, p=1.0). CT utilization for patients with an equivocal ultrasound and SS present decreased (36.4% vs 8.9%, p=0.002) and admissions for observations decreased (21.5% vs 15.3%, p=0.02). Test characteristics of RLQ US for appendicitis also improved in the posttemplate period.

CONCLUSION

A focused QI initiative led to high compliance rates of utilizing the standardized US report and resulted in lower CT use and fewer admissions for observation. Study of a Diagnostic Test Level of Evidence: 1.