Negative Appendicectomy Rates and Implication of Preoperative Imaging: A Retrospective Cohort Study of

appendicectomy [7]. Internationally, a survey of 364 surgeons from America and Europe showed that 64e73% backed the removal of a macroscopically normal appendix [16]. Our study aimed to determine our NAR, to identify the effect of pre-operative Alvarado Scoring / Imaging / Consultant review on NAR and the cost reduction strategies by reducing NAR. Data were collected retrospectively. 100 consecutive patients who underwent both open and laparoscopic emergency appendicectomy in our district general hospital from June 2019 till November 2019. Patients under 18 years old from this study. For our study, AbsTRACT Appendicectomy Rates and Implication Preoperative Imaging: A Retrospective Cohort Study removing that it hide microscopic or other pathology and that


Introduction
Appendicitis was the cause of 40,588 emergency admissions with 33,193 emergency appendicectomies performed in England from April 2012 to March 2013 [1]. There is presently no standard definition of a negative appendicectomy (NA) as it can refer to a macroscopically or histopathologically normal appendix [2,3].
Recent studies from the United Kingdom show NARs that range from 19% to 33.9% [4][5][6][7][8][9]. Internationally, a NAR of 15.3% was reported in 261,134 patients from the United States in 2002 [10]. Brockman et al. summarized 11 recent international large studies to generate a combined NAR of 26% [11]. There is also considerable argument about the management of the normal appendix. The Royal College of Surgeons in Ireland in 2005 issued a Grade B recommendation that a macroscopically normal appendix may be left in situ [12].
This point of view has been strengthened more recently by other authors who argue that removal of a normal appendix increases morbidity and length of stay [10,13]. However, counterarguments in favour of removing the normal appendix are that it can hide microscopic appendicitis or other pathology and that removal does not lead to increased morbidity or complications [5,14,15]. Surgical practice and opinion are similarly divided. In the UK, a multi-center audit in 2013 showed a wide variation in surgical practice regarding appendicitis and appendicectomy [7]. Internationally, a survey of 364 surgeons from America and Europe showed that 64e73% backed the removal of a macroscopically normal appendix [16].

Methods and Materials
Our study aimed to determine our NAR, to identify the effect of

Results:
The negative appendicectomy rate was 22%. With pre-operative CT scan, it came down to 11.5%. If all patients undergo pre-operative CT, with a reduction of 10.5% in negative appendicectomy rate, the overall total cost reduction would be £23,700. Preoperative consultant review did not reduce NAR rather increased.
Conclusion: Finally, our study revealed that the negative appendicectomy rate could be improved by preoperative imaging. Further studies should focus on a consistent CT protocols to reduce the risk of radiation, especially in young adult and females. Negative appendicectomy was defined as a pathologically normal appendix removed from patients suspected with appendicitis.

Results
100 patients were included in this retrospective study ( Figure   1). Average age of patients undergoing appendicectomy 33 years.
Male patients were 47 and Female patients were 53. Female to male ratios 53:47. Number of patients not seen by consultants 37. The negative appendicectomy rate was 22% (Table 1). With pre-operative CT scan, it came down to 11.5%. One patient had preoperative MRI due to pregnancy ( Table 2). Based on the 2018/19 national tariff payment scheme, a CT abdomen and pelvis with contrast and emergency appendicectomy cost 92 and £2370, respectively. The total cost of patients who underwent appendicectomy without imaging was £2,37,000. If all patients undergo pre-operative CT, with a reduction of 10.5% in negative appendicectomy rate, the overall total cost reduction would be £23,700. Preoperative consultant review did not reduce NAR rather increased. Obviously, most of these patients were the patients who underwent diagnostic laparoscopy and the macroscopically normal appendix was removed after no other cause was found. Even though not all patients had sufficient data to calculate Alvarado score, it was not found significant in reduction of NAR (Table 3).

Conclusion
Finally, our study revealed that the negative appendicectomy rate could be improved by preoperative imaging. This study also showed that implementation of preoperative imaging for suspected appendicitis cases would be cost saving, allowing better distribution of resources. Further studies should focus on a consistent CT protocols to reduce the risk of radiation, especially in young adult and females.

Disclosure, Ethics and Funding
No conflicts of interest to disclose. This study was registered with relevant department of the hospital. Data were collected retrospectively, and no patients' identifiable numbers were used.
No funding was involved.