Detection of pinpoint tenderness on the appendix under ultrasonography is useful to confirm acute appendicitis

Hypothesis: Ultrasonography can be efficiently performed using new criteria for the diagnosis of acute appendicitis. Design: Prospective trial. Patients: Eighty-nine patients admitted to the hospital with suspected appe ndicitis between March 1998 and November 2000. Intervention: At hospital admission, a staff surgeon evaluated each patient and determined whether the patient had appendicitis requiring immediate su rgery or another disease. Patients then underwent ultrasonography. A sonogr aphic transducer was placed on the area of maximal tenderness. When the pat hological manifestation was depicted, the examiner slipped a fingertip betw een the transducer and the patient's skin and then pressed the area of depi cted pathological manifestation to find pinpoint tenderness. When maximal p inpoint tenderness was noted on the appendix or on pathological manifestati ons contiguous to the appendix, we diagnosed the condition as appendicitis. Main Outcome Measures: Sensitivity, specificity, positive and negative pred ictive values, and overall accuracy. Results: The diagnosis of appendicitis by this criteria had a sensitivity o f 86.7%, a specificity of 89.7%, a positive predictive value of 94.5%, a ne gative predictive value of 76.5%, and overall accuracy of 87.6%. All 50 pat ients with pinpoint tenderness noted on the appendix had appendicitis. The surgeon's initial clinical impression had a sensitivity of 83.3%, a specifi city of 44.8%, a positive predictive value of 75.8%, a negative predictive value of 56.5%, and overall accuracy of 70.8%. Conclusions: The efficacy of ultrasonography using the simple criteria was superior to that of the surgeon's initial clinical impression (P < .001). O ur ultrasonographic criteria for the diagnosis of appendicitis are simple t o use and efficient.