Sonographic Accuracy in Determining Acute Appendicitis in the Children in a Tertiary Care Hospital

Abstract

Objective:  The purpose of this study was to determine the accuracy of sonographic diagnosis in patients with suspected acute appendicitis in a tertiary care hospital, utilizing commercially available 3.75 MHz curved array probe. Most of the stu-dies on this subject have used high frequency probes and therefore report very high sensitivities and specificities.

Material and Methods:  220 paediatric patients (range 3-14 years, mean age 11.3 years) attending the Emergency Depart-ment Of Lahore General Hospital Lahore with clinical suspicion of acute appendicitis were evaluated by the author. Children with vague abdominal pain or without suspicion of acute appendicitis were not in included in the study. Four criteria i.e. enlarged appendix (diameter more than 6 mm), lack of compressibility, a blind ending loop without peristalsis and localized fluid collection were taken into consideration before declaring a patient to be having acute appendicitis.

Results:  Sonography confirmed the diagnosis in 39 out of 54 patients whereas 15 patients, falsely reported to be normal on sonography, were found to be having acute appendicitis on surgery. False positive diagnosis was made in 6 patients, all of whom underwent appendectomy. 160 patients declared normal on sonography proved to be normal on observations during hospital stay and follow up. Sensitivity of 72% achieved in this study was lower than reported in current literature employing high frequency probes. Specificity 96%, accuracy 91%, negative and positive predictive values of 92 and 87% respectively fall within described range of quoted results.

Conclusion:  Though sensitivity achievable with the medium frequency ultrasound probe is a little lower than that declared in recent similar studies, author believes that given the availability of this probe and considering the cost effectiveness, use of standard commercially available 3.75 MHz probe is quite effective in making a diagnosis of acute appendicitis and should be encouraged so that a sizeable portion of unnecessary appendectomies can be avoided.

Key words:  Acute appendicitis, sonography, children, tissue harmonic imaging.