EP198 - Negative appendicectomy: A cohort study

Abstract Aims Negative appendectomy is charaterized as removal of normal appendix histopatholigically. Diagnosis of appendicitis remains a challenge, despites improved diagnostic algorithms (including scoring systems, serological & radiological tests), negative appendectomy rate remains < 20%. The aim of the study is to assess negative appendicectomy at a single centre. Methods Cohort study was carried out on all appendicectomies from Mar’2020 to Jan’2024. Descriptive demography & post-operative outcomes were evaluated for negative appendicectomies (Histopathological HPA confirmed normal appendix), all other appendicectomies (HPA confirmed appendicitis) were recruited as controls. Results Normal HPA(n = 41) Appendicitis HPA(n = 477) Mann-Whitney U(p value) Age(yrs) 26.4 36.7 < 0.005 Sex(M : F) 16 : 25 235 : 242 NS BMI(kg/m2) 24.7 25.5 NS GP 8 135 NS A & E 33 342 NS WCC(x109/L) 10.7 13.5 < 0.0001 CRP(mg/L) 43.4 ± 10.5 68.3 ± 3.9 < 0.005 Open(n) 0 8 NS Lap(n) 41 469 NS ASA(median) 1 1 NS Diagnostic(n) Clinical 0 33 USS scan 23 117 < 0.001 CT scan 18 327 < 0.01 AB (days) Inpatient 2 ± 0.5 2 ± 1 NS Discharge 0 ± 2 ± 2.5 < 0.005 Operation time (mins) 66.2 75.7 < 0.01 LOS (days) (med) 2 2 NS Appendix HPA (mm) Length 62.4 67.0 NS Diameter 8.6 11.5 < 0.0001 Cost (£) 3376 4341 < 0.05 Conclusions Despite radiological diagnostics, the negative appendicectomy rate was 7.9 %. Laparoscopy offers an additional diagnostic modality especially in women & post op recovery is quicker. The negative appendicectomy rate has been declining in recent years, but cannot be abolished. A negative appendicectomy rate of < 10 % must be deemed acceptable, to achieve a 90 % therapeutic appendectomy (HPA confirmed appendicitis) rate.