title: Appendiceal outer diameter as an indicator for differentiating appendiceal mucocele from appendicitis.
abstract: BACKGROUND
  Patients with appendiceal mucocele (AM) commonly present with features indicative of acute appendicitis. In emergency departments, accurate preoperative diagnosis is crucial to prompt appropriate treatment. This study investigates the clinical and sonographic characteristics of AM, which may prove useful in preoperatively differentiating AM from appendicitis.
  
  
  METHODS
  This case-control study compares the clinical and sonographic findings of 16 histologically confirmed AM with sex- and age-matched control subjects (n = 64) with appendicitis by a 1:4 ratio. Conditional logistic regression was applied to estimate the odds ratio (OR) and 95% confidence intervals (CI) of clinical and sonographic parameters associated with AM.
  
  
  RESULTS
  Univariate analysis demonstrated that the larger appendiceal outer diameter by sonography was positively correlated with diagnosis of AM (OR, 2.31; 95% CI, 1.42-3.72) and right lower quadrant abdominal pain was negatively correlated (OR, 0.38; 95% CI, 0.17-0.82). However, multiple regression analysis suggested that only outer diameter remained significant (OR, 2.21; 95% CI, 1.36-3.59) after adjusting for age, sex, and right lower quadrant pain. An outer diameter of 15 mm or more was predictive of AM diagnosis, with a sensitivity of 83% and specificity of 92%.
  
  
  CONCLUSIONS
  When the threshold is set at 15 mm, appendiceal outer diameter by sonography is a useful preoperative measurement for differentiating between AM and acute appendicitis.
authors.affiliation: Department of Emergency Medicine, College of Medicine, National Taiwan University and National Taiwan University Hospital, Taipei 100, Taiwan.
authors.forename: Wan-Ching
authors.initials: WC
authors.lastname: Lien
authors.forename: Shih-Pei
authors.initials: SP
authors.lastname: Huang
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Chi
authors.forename: Kao-Lang
authors.initials: KL
authors.lastname: Liu
authors.forename: Ming-Tsan
authors.initials: MT
authors.lastname: Lin
authors.forename: Ting-I
authors.initials: TI
authors.lastname: Lai
authors.forename: Yueh-Ping
authors.initials: YP
authors.lastname: Liu
authors.forename: Hsiu-Po
authors.initials: HP
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy; D001064:Appendicitis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D001065:Appendix / Q000000981:diagnostic imaging* / Q000473:pathology*; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009078:Mucocele / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D012680:Sensitivity and Specificity; D014463:Ultrasonography