[Experimental ultrasound analysis of the appendix. Contribution to improving the diagnosis of acute inflammation in routine clinical practice].

Sonographic investigations of fresh operative specimens - 50 non-infected, 50 chronic and 50 acute inflammatory appendices - and also of 335 pertinent operated patients with "typical" appendiceal disorders were performed. All other entities, mimicking acute or perforated appendicitis were excluded from this study. Under experimental conditions, negative, chronic and acute or phlegmonous appendices appeared as "cockade" or "pseudokidney sign" with reflecting wall and echoless lumen. The application of a 5 Mz linear transducer made the differentiation of three wall layers feasible, in negative appendices as well as in dilated acute appendicitis, whereas in chronic inflammation and in obliterating acute appendicitis a wall layer stratification was not possible. In clinical application of 335 operated patients we only could demonstrate cases of acute or perforated appendicitis (n = 182/220), but no cases of non-infected appendix. In 57% of pertinent cases the objectivation of lumen dilatation, in 35% a wall layer stratification was feasible. Acute, phlegmonous or perforated appendicitis was proven by demonstrating an immobile "pseudotumor mass" with dominating constant hypodense reflex property. The pertinent diameters as measured in clinical acute appendicitis exceeded significantly the diameters observed in experimental sonography of negative appendices with a differential intact mobility. Intraluminary coproliths and hyperdense reflecting attached omental segments facilitated a sonographic diagnosis. In 101/115 patients correct negative diagnosis was established. On the basis of these criteria, a sensitivity of 83%, a specificity of 88% and a diagnostic accuracy of 85% related to the diagnosis of acute or perforated appendicitis was obtained in this study.