Ultrasonography in acute appendicitis - Body mass index as selection factor for US examination

Purpose: Acute appendicitis is often difficult to diagnose and a negative laparotomy rate of about 25% is common. At Danderyd Hospital we started routine US in these patients, the aim being to estimate the sensitivity and the specificity for US when compared with the body mass index (BMI) of the patient. Material and Methods: AU patient records were examined: During a period of 6 months 142 patients over 14 years of age were investigated with US. Their height and weight were noted and the BMI was calculated. Results: The sensitivity for US examination was 0.76 in patients with a BMI <25 but only 0.37 in patients with BMI greater than or equal to 25. This difference was statistically significant. Conclusion: US is a good method for examination of patients with BMI less than 25 but not in patients with BMI over 25.