INTEROBSERVER VARIABILITY IN ULTRASOUND SCAN FOR SUSPECTED ACUTE APPENDICITIS

<b>BACKGROUND:</b> There is a global resolve among Clinicians towards adoption of imaging modalities in the evaluation of appendicitis because clinical algorithms have been disappointing. We sought to determine the authenticity of interobserver variability in ultrasound scan in a resource-constrained mission hospital settings, northwestern region of Cameroon. <b>METHODS:</b> In this study, we reviewed the standardized diagnostic approach in acute appendicitis and also performed prospective cross observational qualitative testing using sensitivity, specificity, positive predictive value, negative predictive value, and accuracy to determine the interobserver variability of ultrasonography using the medical database of the two Mission Hospitals, northwestern region of Cameroon from January 2012 to December 2016. A sequential non-randomized convenient sampling was used and data was analyzed using the Statistical Package for the Social Sciences version 22. <b>RESULTS: </b>A total of 103 patients who had pre-operative evaluation with Ultrasound scan and subsequently underwent surgery with histo-pathological examination of the removed appendix were analyzed. Their ages ranged from 15 to 65 years with a mean age of 30.6±18. There were 62 males and 41 females with a ratio of 1.5:1. Of the 103 patients, (n=90; 87.4%) cases were diagnosed as AA by histopathology while (n= 9; 8.7%) cases were negative. Ultrasound was positive in (n=75; 72.8%) cases, equivocal in (n=16; 15.5%), and negative in (n=10; 10.4%) cases. Sensitivity of ultrasound from this study when compared with ultrasound as the gold standard was 90.2% with a specificity of 85.6%; while Overall accuracy was 72.4%. Age and gender had no significant relationship with the accuracy of ultrasound in this study (p value=0.2 and 0.7 respectively). <b>CONCLUSION:</b> Ultrasound scan is more useful in detecting than in ruling out appendicitis. The radiological criteria for acute appendicitis, the accuracy of various imaging modalities and the limitations of the available research are described in this series. The interobserver variability in the ultrasonography evaluation of appendicitis is of significant impact in resource- limited surgical emergency settings like ours, which is a rural tropical population in the developing country.

**背景：** 全球临床医师已普遍倾向于采用影像学手段评估阑尾炎，因临床诊疗算法的效果不尽如人意。本研究旨在评估喀麦隆西北部地区资源匮乏的教会医院环境下，超声扫描（ultrasound scan）中观察者间变异（interobserver variability）的真实性。
**方法：** 本研究回顾了急性阑尾炎（acute appendicitis）的标准化诊疗方案，并利用喀麦隆西北部两家教会医院2012年1月至2016年12月的医疗数据库，采用灵敏度、特异度、阳性预测值、阴性预测值及准确度作为评价指标，开展前瞻性交叉观察定性研究，以分析超声扫描的观察者间变异。本研究采用连续性非随机便利抽样方法，数据通过社会科学统计软件包（Statistical Package for the Social Sciences，SPSS）22.0版进行分析。
**结果：** 本研究共纳入103例术前接受超声扫描评估、后续接受手术并对切除阑尾行组织病理学检查的患者。患者年龄范围为15~65岁，平均年龄为30.6±18岁。其中男性62例，女性41例，男女比例为1.5:1。103例患者中，90例（87.4%）经组织病理学确诊为急性阑尾炎（acute appendicitis，AA），9例（8.7%）结果为阴性。超声扫描结果阳性75例（72.8%）、可疑16例（15.5%）、阴性10例（10.4%）。以组织病理学检查为金标准时，本研究中超声扫描的灵敏度为90.2%，特异度为85.6%，总体准确度为72.4%。本研究显示，年龄与性别均与超声扫描的准确度无显著相关性（分别对应P值0.2与0.7）。
**结论：** 超声扫描在阑尾炎的确诊方面优于排除诊断。本系列研究阐述了急性阑尾炎的影像学诊断标准、各类影像学手段的诊断价值及现有研究的局限性。在类似本研究的资源有限的外科急诊场景（即发展中国家热带农村地区人群）中，阑尾炎超声评估中的观察者间变异会产生显著影响。