Purpose: To evaluate the role of ultrasound in the diagnosis of acute appendicitis and present ultrasonographic grading 
for the disease 
Material and Methods: This is a prospective controlled study of 232 patients with suspected acute appendicitis and 120 
controls. All patients and controls underwent ultrasonographic examination, then divided into3 groups : group 1 (=100 
patients) who proved surgically that they have acute appendicitis, group 2 (= 132 patients) who proved to have acute 
abdominal conditions other than appendicitis and group 3 (= 120 controls) 
Results: In group I the inflamed appendix appeared as hypoechogenic shadow with thick fluid collection inside the lumen. 
The diameter of the wall of the inflamed appendix was 5 to 35 mm. A diameter more than 6 mm confirmed the diagnosis of acute appendicitis. The US findings seen in patients with acute appendicitis are presented and graded according to the severity. To our knowledge we are the first to present this ultrasonographic grading. In group II and III, the previous 
ultrasonographic findings were absent and the diameter of the wall of the appendix was between 2 and 4 mm. 
Conclusion: ultrasonographic findings are useful in confirming the diagnosis of acute appendicitis and a normal ultrasoud exam is more useful in ruling out acute appendicitis. The ultrasonographic criteria can be graded and this grading might be helpful in assessing the severity of the disease.