Graded compression ultrasound scan (USS) has been widely used to look for appendicitis in patients with RIF pain. It has an overall accuracy of about 90% (sensitivity 84% and specificity 88%), but is very operator dependent [7,11-12]. A USS can rule in appendicitis but cannot rule it out, i.e. in the presence of a normal scan the patient will still need to be closely observed.
USS is of particular value in trying to identify other pathologies, especially in women of child-bearing age, when the diagnosis may be unclear. It is also of benefit in patients with atypical signs, such as the elderly, children or pregnant patients.