When does ultrasonography influence management in suspected appendicitis?

BACKGROUND: Accurate diagnosis of appendicitis is challenging, particularly in children. Moreover, opinion is divided over the role of ultrasonography (US) in its diagnosis and how US may influence management. This study compares the use of US in two tertiary paediatric hospitals and how it influenced the management of suspected appendicitis. METHODS: Data from acute admissions, radiology, histopathology and theatre were cross-referenced to review all children who underwent an appendicectomy (with or without preoperative US) for suspected appendicitis in Christchurch (CH) in New Zealand and Aberdeen (AB) in Scotland in 2009. RESULTS: Five hundred and ninety-nine patients (442 CH; 157 AB) were included, with similar age and gender distributions. US was performed in 23% of patients with an overall appendix visualization rate of 29%. The overall positive and negative predictive values were 67% and 100%, respectively. Females were more likely to have US than males (P < 0.001, χ(2) ). In females with no appendix seen on US, in the presence or absence of other pathology, a normal appendix was confirmed in 50% and 58%, respectively. Visualizing the appendix resulted in a lower rate of normal appendix at operation (20%, 4/20) compared with when the appendix was not visualized (56%, 14/25). CONCLUSION: Identification of a normal appendix on US seems sufficiently accurate to exclude appendicitis with confidence, while positive US should be interpreted in conjunction with the clinical features in influencing the decision to operate. The incidence of a non-inflamed appendix at operation could be reduced with an increased rate of appendiceal visualization by sonographers.