Negative Appendicectomy Rate and Surgery Despite Negative Triple-Screen Inflammatory Markers in Children: A Single-Centre Retrospective Cohort Study.

Introduction  The negative appendicectomy rate (NAR) is an important measure of diagnostic accuracy and quality of care. Diagnosing appendicitis in children remains challenging due to frequently atypical and non-specific clinical presentations. Despite advances in clinical scoring and imaging, NAR in the UK remains high. The primary aims of this audit were to determine the NAR at Queen's Hospital Burton against the Getting It Right First Time (GIRFT)-reported national figure, and to establish how often surgery proceeded despite negative Academy of Medical Royal Colleges (AoMRC) triple-screen inflammatory markers, to inform review of the local diagnostic pathway. Exploratory analyses examined the association of Paediatric Appendicitis Score (PAS) risk category and preoperative imaging with NAR.  Methods  This retrospective, single-centre, single-cycle audit included 318 children aged 5-16 years who underwent surgical exploration for suspected acute appendicitis between December 2017 and June 2026; 302 had appendicectomy with available histopathology and were included in the primary analysis. Data were retrospectively collected from electronic patient records, including demographics, inflammatory markers, imaging, histopathology, and post-operative complications. Negative appendicectomy was defined histologically as the absence of inflammatory changes. Triple-screen-negative was defined as CRP <10 mg/L, WCC <10.5 ×10⁹/L, and neutrophil percentage <75% on the first pre-operative sample. As secondary, exploratory analyses, the PAS was reconstructed retrospectively, blinded to histopathology, and the association of PAS risk category and preoperative imaging with NAR was examined. Statistical analysis used Microsoft Excel for the web (Microsoft Corp., Redmond, WA), with Fisher's exact test and ROC/AUC analyses performed in GraphPad (Dotmatics, Boston, MA) and jamovi (https://www.jamovi.org), respectively.  Results  Of 302 children who underwent appendicectomy with available histopathology, the NAR was 21.2% (95% CI 17.0-26.1%), significantly higher than the GIRFT-reported national figure of 10% (two-sided exact binomial test, p<0.0001). Of 318 children explored, 55 (17.3%) met AoMRC triple-screen-negative criteria yet proceeded to surgery; among the 49 with histopathology, the NAR was 73.5% (36/49; 95% CI 59.7-83.8%). In exploratory analyses, NAR fell across PAS risk categories, from 50.0% (low risk) to 31.1% (equivocal risk) to 10.0% (high risk) (χ² p≈1.65×10⁻⁶), and PAS had an AUC of 0.730 (95% CI 0.663-0.798) for appendicitis. Imaging use declined from low risk (52.6%) to high risk (27.6%). Within the equivocal-risk group, NAR was higher among imaged than non-imaged patients (48.9%, 23/47 vs 21.2%, 18/85; OR 3.57, 95% CI 1.65-7.73; Fisher's exact p=0.0015).  Conclusion  NAR at this centre significantly exceeded the GIRFT-reported national figure. A substantial minority of children who underwent surgery (17.3%) met AoMRC triple-screen-negative criteria, and the NAR in this subgroup was high. These findings identify an opportunity to review the local diagnostic pathway. Prospective evaluation is required to determine whether standardised, combined use of a validated clinical scoring system (PAS), biochemical inflammatory markers, and imaging can reduce unnecessary appendicectomy without increasing missed or delayed diagnoses.