Benefits of ultrasound vs. computed tomography in the diagnosis of pediatric lateral neck abscesses.

Objective: There are no studies comparing the accuracy of ultrasound and computed tomography in the same population of pediatric patients with lateral neck abscesses. This case series assesses the accuracy of the two imaging techniques.

Methods: One hundred and forty imaging studies (ultrasound n=39 or CT n=101) that were performed from 2005 to 2011 prior to incision and drainage of a lateral neck mass at a tertiary care academic institution were retrospectively reviewed. All children 0-18 years of age with lateral neck abscesses who underwent CT or ultrasound imaging prior to drainage were included. Sensitivity, specificity, and positive and negative predictive values of ultrasound and CT were determined as compared to the gold standard, incision and drainage of the suspected abscess.

Results: In children undergoing incision and drainage, the prevalence of an abscess was 89%. Ultrasound has a high specificity (100%) but a low sensitivity (53%). The positive predictive value (96%) is high while the negative predictive value is low (16%), assuming a positive abscess prevalence of 0.9. In contrast, CT has low specificity (18%) but slightly higher sensitivity (68%) compared to ultrasound. Similar to ultrasound, CT had low negative (6%) and high positive (88%) predictive values.

Conclusions: This study demonstrates that ultrasound may be an equivalently sensitive and more specific diagnostic tool when compared to CT in the work-up of lateral neck abscesses in children. It is safe and effective in diagnosis when there is an undetermined probability of an abscess.