Appendicitis: evaluation of sensitivity, specificity, and predictive values of US, Doppler US, and laboratory findings.
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.
Kessler
Nicolas
N
Department of Radiology, Lapeyronie Hospital, 371 Avenue du Doyen Gaston Giraud, 34295 Montpellier 5, France.
Cyteval
Catherine
C
Gallix
Benoît
B
Lesnik
Alvian
A
Blayac
Paul-Marie
PM
Pujol
Joseph
J
Bruel
Jean-Michel
JM
Taourel
Patrice
P
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
D002097:C-Reactive Protein