How does diagnostic accuracy of US in suspected acute appendicitis differ depending on operator competency?

Transcription

1 How does diagnostic accuracy of US in suspected acute appendicitis differ depending on operator competency? Poster No.: C-2102 Congress: ECR 2012 Type: Authors: Scientific Exhibit J. Dunn 1, M. A. Arshad 2, D. Fascia 1, D. ap Dafydd 1 ; 1 London/UK, 2 1NY/UK Keywords: DOI: Acute, Outcomes analysis, Ultrasound, Emergency, Abdomen /ecr2012/C-2102 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 6

2 Purpose Ultrasound examination in cases of clincally suspected appendicitis has a great variability in sensitivity and specificity and is highly operator dependent 1,2. To review data concerning the diagnostic accuracy of ultrasound examination in cases of acute appendicitis at a single institue. To establish the diagnostic accuracy depending on operator competancy between consultants (5+ years of radiology experience) and registrars (1-5 years of radiology experience) in performing ultrasound examinations in patients with clinically suspected appendicitis. Images for this section: Fig. 1: Normal appendix Page 2 of 6

3 Fig. 2: Abnormal appendix Page 3 of 6

4 Methods and Materials All Reports containing the keyword "appendicitis" were retrospectively obtained between January 2008 and April 2010 from a report archive system at St. Mary's Hospital, London. Any report where the word "appendix" was mentioned but appendicitis was not actually clinically suspected, such as post-appendicectomy, were excluded. The ultrasound results were classed "US positive" or "US negative". In terms of the data analysis "US negative" cases included "normal appendix", "appendix not seen" and "equivocal" cases. "Equivocal" cases were included in the "US negative" category as they did not advance the diagnostic process (the cases are already equivocal on clinical grounds, hence the reason for the US in the first place). The ultrasound study results were correlated with respective histopathology reports and discharge summaries for follow up, to determine clinical outcome. The outcomes were as follows: 1. No pathology report. 2. Normal appendix on pathology. 3. Appendicitis proven on pathology. 4. Alternative pathology at appendicectomy. Results US reports for 529 cases of clinically suspected appendicitis (mean age, 28 years; range years) were obtained. A total of 134 patients had pathologically proven appendicitis, of which 64 had positive findings on ultrasound. The overall sensitivity was 48% (95% confidence interval (CI): 39%, 56%) and the specificity was 97% (95% CI: 95%, 99%). The positive predictive value (PPV), negative predictive value (NPV) were 84% and 85%. The overall negative appendicectomy rate was 27%. 208 US examinations were performed by consultants compared to 321 performed by registrars. The diagnostic accuracy of consultants compared to registrar was 89% versus Page 4 of 6

5 82%.The sensitivity and specificity of examinations performed by consultants was 59% and 98% compared to 41% and 96% respectively performed by registrars. Of the cohort of scans performed by consultants, the negative appendicectomy rate was 14%, compared to 31% in the registrar cohort. Images for this section: Fig. 3: Results Page 5 of 6

6 Conclusion Ultrasound, combined with accurate clincial examination can improve the diagnosis of clinically suspected appendicitis, however it is not a sensitive test. Our study has shown that operator competancy can affect the sensitivity of ultrasound in diagnosing clinically suspected appendicitis and negative appendicectomy rates. Whilst it may be the case that the majority of ultrasound studies performed by a registrar at our institute, were in an emergency setting out of hours, with both pressure of time and the surgical team. Operator competence improves the diagnostic accuracy of ultrasound, therefore reducing negative appendicectomy rates. Emphasis should be placed on focused registrar training in the ultrasound of clinically suspected appendicitis. References 1.Terasawa T et al. Systematic review: computed tomography and ultrasonography to detect acute appendicitis in adults and adolescents. Ann Intern Med Oct 5;141(7): Poortman P et al. Improving diagnosis of acute appendicitis: results of a diagnostic pathway with standard use of ultrasonography followed by selective use of CT. J Am Coll Surg Mar;208(3): Personal Information Page 6 of 6