Cohort study of 1241 patients to identify predictors of negative appendicectomy

Abstract

Background: Acute Appendicitis is the most common surgical presentation within Australia. Despite the increasing use of radiological investigations to aid clinical diagnosis, many appendectomies result in a histologically normal appendix. This study examines the histological negative appendicectomy rate (NAR) in a metropolitan hospital and determine factors associated with a negative appendicectomy (NA). Methods: Patients who underwent emergency appendicectomy for suspected acute appendicitis at Logan Hospital, Australia, between February 2016 and March 2019 inclusive were included. Clinicopathologic and imaging variables were analysed for associations with NA. Results: A total of 1241 patients underwent emergency appendicectomy of which 121 patients (9.8%) had a NA. The NAR for clinical diagnosis alone (no imaging) was 9.9%, 14.5% for ultrasonography alone and computed tomography scan alone was 4.9%. Univariate analysis revealed age <27 years (P < 0.001), absence of hypertension (P = 0.008), symptoms >48 hours (P < 0.001), absence of leucocytosis (P < 0.001), undergoing ultrasonography only (P < 0.001), undergoing computed tomography scan only (P < 0.001), macroscopically normal appendix (P < 0.001) and time to operation >24 hours (P < 0.001) were associated with NA. Multivariate analysis identified symptoms >48 h at presentation (odds ratio (OR) 1.98, 95% confidence interval (CI) 1.20-3.24; P = 0.007), absence of leucocytosis (OR 2.41, 95% CI 1.52-3.81; P < 0.001) and macroscopically normal appendix (OR 5.70, 95% CI 3.49-9.33; P < 0.001) to be associated with a NA. Conclusion: The NAR reported is lowest in an Australian institution. The identified predictors of NA will be useful in identifying patients who would truly benefit from an appendicectomy versus those would have a higher rate of NA who may be suitable to be treated non-operatively to be spared the unnecessary morbidity of surgery.

Quality Outcomes in Appendicitis Care: Identifying Opportunities to Improve Care

“…Our study is in keeping with the literature which shows female patients have higher negative appendectomy rates and morbidity associated with it [ 21 , 26 , 27 , 28 ]. Mackey et al recently identified factors that may be associated with higher negative appendicectomies, including independent factors such as age below 27, duration of symptoms for more than 48 h, normal leucocyte count, use of single imaging modality (ultrasound or CT) and time to operation greater than 24 h. Combination of factors like symptoms more than 48 h, normal leucocyte count, and a macroscopically normal intraoperative appendix may also be associated with a negative appendicectomy, but they also discussed that an intraoperatively normal looking appendix was histologically confirmed as normal only in 41%, hence the decision to not perform an appendicectomy in the absence of other pathologies still requires further studies where long-term effects of the practice are highlighted [ 29 ].…”

“…Mackay et al suggested that a delay in surgery beyond 48 h may be a predictor of negative appendicectomy, as the urgently operated patients usually have a clear presentation, whereas patients where diagnostic laparoscopy is the final investigation, an appendicectomy may be done contributing to morbidity associated with surgery. Instead, they suggest that the role of re-imaging needs consideration as a cost-effective and less invasive option [ 29 ].…”

“…Therefore, a balance is suggested in the Jerusalem Guidelines, where US scanning may still help reduce CT scanning by 50% and also, backed by the OPTICAP study, utilisation of low-dose CT scanning may reduce the mean radiation dose to 3.33 mSv while maintaining the accuracy [ 10 , 43 , 44 ]. In our study, the combined conditional approach to CT was used in only 3%, whereas a combined approach may reduce negative appendicectomy rate as well, and may be considered as the approach of choice in the future [ 29 ].…”

Risk factors associated with negative appendicectomy rates: A retrospective cohort study

“…Though this is in contrast to some of the existing literature. 8, 19,24,25 , other studies have suggested WBC is not a predictor of AA. 26 Furthermore it has been suggested that WBC is a poor predictor of AA due to an unreliable speci city and sensitivity and there is no consensus for a reliable cut off value.…”