Purpose : To evaluate the role of ultrasound in the diagnosis of acute appendicitis, especially, atypical cas­es and mimicking conditions.
Patient and Methods : This is a prospective controlled study of 858 patients with suspected acute appen­dicitis and 240 controls. All patients and controls underwent ultrasono-graphic examination, then divided into 3 groups : group I (284 patients) who were proved sonographically and sur­gically that they have acute appendi­citis, group II (574 patients) who proved to have acute abdominal con­ditions other than appendicitis includ­ing cases with false negative and
false positive results by US, group III (240 controls).
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Results : In group I the inflamed appendix appeared as hypoechogen-ic shadow with thick fluid collection in­side the lumen. The diameter of the wall and lumen of the inflamed ap­pendix was ranging between 4 to 35 mm. Early cases were characterized sonographically by thickening of the wall of the appendix between, 4 to 6 mm, non-compressible aperistaltic appendix, in homogeneous content and sometimes faecolith or gas inside the lumen, late cases were character­ized by thickening of the appendicu-lar wall > 6 mm, free liquid collec­tions