Diagnostic Accuracy of Suspected Appendicitis: A Comparative Analysis of Misdiagnosed Appendicitis in Children.

Objective: When evaluating suspected appendicitis, limited data support quality benchmarks for negative appendectomy (NA); none exist for delayed diagnosis of appendicitis (DDA). The objectives of this study are the following: (1) to provide preliminary evidence supporting a quality benchmark for DDA and 2) to compare presenting features and diagnostic evaluations of children with NA and DDA with those with pathology-confirmed appendicitis (PCA) diagnosed during initial emergency department (ED) encounter.

Methods: Secondary analysis of data from a QI project designed to reduce the use computed tomography when evaluating suspected appendicitis using a case-control design. Patients undergoing appendectomy in an academic tertiary care children's hospital system between January 1, 2015, and December 31, 2016 (n = 1,189) were eligible for inclusion in this case-control study. Negative appendectomy was defined as no pathologic change or findings consistent with a different diagnosis. Delayed diagnosis of appendicitis was defined as patients undergoing appendectomy within 7 days of a prior ED visit for a related complaint. Controls of PCA (n = 150) were randomly selected from all cases undergoing appendectomy.

Results: There were 42 NA (3.5%) and 31 DDA (2.6%). Cases of PCA and NA exhibited similar histories, examination findings, and underwent comparable diagnostic evaluations. Cases of PCA more frequently demonstrated a white blood cell count greater than 10 × 103/μL (85% vs 67%; P = 0.01), a left-shift (77% vs 45%; P < 0.001), and an ultrasound interpretation with high probability for appendicitis (73% vs 54%; P = 0.03). Numerous significant differences in history, examination findings, and diagnostic tests performed existed between cases of PCA and DDA.

Conclusions: Children with PCA and NA present similarly and undergo comparable evaluations resulting in appendectomy. A 3% to 4% NA rate may be unavoidable given these similarities. Presenting features in DDA significantly differ from those of PCA. An irreducible proportion of appendicitis diagnoses may be delayed.