title: Appendicitis: evaluation of sensitivity, specificity, and predictive values of US, Doppler US, and laboratory findings.
abstract: OBJECTIVE
  To evaluate the sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of ultrasonography (US), Doppler US, and laboratory findings in the diagnosis of appendicitis.
  
  
  METHODS
  A total of 125 consecutive patients suspected of having appendicitis were prospectively included for US appendiceal (diameter enlarged to 6 mm or greater, intraluminal fluid, lack of compressibility) and periappendiceal (periileal inflammatory changes, cecal wall thickening, periileal lymph nodes, peritoneal fluid) evaluation, Doppler US evaluation (appendiceal wall signal), and laboratory assessment (leukocytosis, C-reactive protein [CRP]). Definite diagnoses were established at surgery in 61 patients, at endoscopy with biopsy in two patients, and at clinical follow-up in 62 patients.
  
  
  RESULTS
  The prevalence of appendicitis was 46%. The appendix was identified with US in 86% of the patients, which included 96% of patients with and 72% of patients without appendicitis. The most accurate appendiceal finding for appendicitis was a diameter of 6 mm or larger, with a sensitivity, specificity, NPV, and PPV of 98%. The lack of visualization of the appendix with US had an NPV of 90%. The most accurate periappendiceal finding of appendicitis was the presence of inflammatory fat changes, with an NPV of 91% and a PPV of 76%, whereas other findings had both NPV and PPV less than 65%. An increase in both white blood cell (WBC) count and CRP level had a PPV of 71%, whereas combined normal WBC count and CRP value had an NPV of 84%.
  
  
  CONCLUSIONS
  A threshold 6-mm diameter of the appendix under compression is the most accurate US finding for appendicitis and has high NPV and PPV.
authors.affiliation: Department of Radiology, Lapeyronie Hospital, 371 Avenue du Doyen Gaston Giraud, 34295 Montpellier 5, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Kessler
authors.forename: Catherine
authors.initials: C
authors.lastname: Cyteval
authors.forename: Benoît
authors.initials: B
authors.lastname: Gallix
authors.forename: Alvian
authors.initials: A
authors.lastname: Lesnik
authors.forename: Paul-Marie
authors.initials: PM
authors.lastname: Blayac
authors.forename: Joseph
authors.initials: J
authors.lastname: Pujol
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Bruel
authors.forename: Patrice
authors.initials: P
authors.lastname: Taourel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy; D001064:Appendicitis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D001065:Appendix / Q000098:blood supply / Q000473:pathology; D001783:Blood Flow Velocity / Q000502:physiology; D002097:C-Reactive Protein / Q000032:analysis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler
chemical_list: D002097:C-Reactive Protein