Outer diameter of the vermiform appendix as a sign of acute appendicitis: evaluation at US.
OBJECTIVE
To evaluate the usefulness and limitations of the outer diameter of the vermiform appendix at cross-sectional ultrasonography to confirm or rule out acute appendicitis.


METHODS
In a prospective study, outer appendiceal diameters in 240 control subjects and in 278 patients suspected of having acute appendicitis who did (n = 98) or did not (n = 180) have acute appendicitis were measured.


RESULTS
Outer appendiceal diameters in the control subjects ranged between 2 and 13 mm, and in 55 (23%) of 240 control subjects, diameters were 6 mm or more. Diameters in the symptomatic patients without acute appendicitis ranged between 2 and 11 mm, and 57 (32%) of 180 patients had diameters of 6 mm or more. Diameters of acutely inflamed appendices ranged between 6 and 30 mm. A diameter of 6 mm or more confirmed acute appendicitis with a sensitivity of 100%; a specificity of 68%; positive and negative predictive values of 63% and 100%, respectively; and an accuracy of 79%.


CONCLUSIONS
The outer appendiceal diameter of 6 mm or more as a sign of acute appendicitis provides high sensitivity but limited specificity. This diagnostic criterion is more useful in excluding acute appendicitis than in confirming it.
Departments of Radiology and Nuclear Medicine, Hospital Barmherzige Brueder, Salzburg, Austria. thomas.rettenbacher@uklibk.ac.at
T
T
Rettenbacher
A
A
Hollerweger
P
P
Macheiner
L
L
Rettenbacher
F
F
Tomaselli
B
B
Schneider
N
N
Gritzmann
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D001064:Appendicitis / Q000000981:diagnostic imaging*; D001065:Appendix / Q000000981:diagnostic imaging*; D002648:Child; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014463:Ultrasonography