Influence of ultrasonography on clinical decision making in suspected acute appendicitis in adults

Summary BACKGROUND: The clinical diagnosis of acute appendicitis is based on the case history and physical examination, which play a major role in decision for operation. We assessed a diagnostic gain of ultrasonography performed by an experienced radiologist in patients with signs suspicious of acute appendicitis. METHODS: In 300 consecutive patients with suspected acute appendicitis besides the clinical examination ultrasound examination was performed. The sensitivity, specificity, accuracy, negative and positive predictive value and the rate of negative laparotomy were calculated. The outcome was correlated with examiners' experience and the efficacy of different probes was compared. RESULTS: The sensitivity was 91.0%, specificity 95.9%, negative predictive value 90.8%, positive predictive value 95.9%, and accuracy 93.3%. The negative laparotomy rate was 4.8%. The examiner's experience had a significant influence on examination outcome. In 23.8% the inflamed appendix could not be visualized with the high-frequency linear probe, while in 9.5% both probes were equally effective. CONCLUSIONS: Ultrasonography is a highly accurate diagnostic procedure in the evaluation of acute appendicitis, when performed by an experienced sonologist, using probes with a wide frequency range. When performed routinely a very low rate of negative laparotomies may be achieved.