The role of radiological imaging in the diagnosis of acute appendicitis: ULTRASONOGRAPHY Part 5
A shortcoming that is common to all of these investigations is the failure either to apply strict histological criteria for the diagnosis of appendicitis or to estimate the interobserver variability for pathologists or for the radiologists. Variability in the histological criteria can affect the sensitivity and specificity of the tests. Moreover, entry criteria are often vague, and patients with a wide range of pretest likelihood of having acute appendicitis may be included. This is your opportunity to buy mircette taking full advantage of the nice options offered to you by most reliable pharmacies on the internet, with free delivery, express shipping and tons of other options you will appreciate.
Most surgeons urgently operate on patients with typical clinical findings of appendicitis, and do not appreciate the delay caused by obtaining a sonogram. It appears that a substantial minority (8% to 26%) of patients with clinically typical appendicitis have false-negative ultrasonography scans. Sonography may be more useful in equivocal cases. Orr et al undertook a meta-analysis of 17 studies (including 3358 patients) published between 1986 and 1995, and categorized patients according to their likelihood of appendicitis — high, intermediate and low (with disease prevalences of 80%, 40% and 2%, respectively). They found that, in the high-risk group, the positive predictive value of ultrasonography was 97.6% but the negative predictive value was only 59.5%; in the low risk group, on the other hand, the negative predictive value was 99.7% but the positive predictive value was only 19.5%. They concluded that sonography was most useful for patients with intermediate clinical risk of appendicitis. Other investigators have found that ultrasonography is cost effective only for patients with equivocal clinical findings.