Objective: To determine the accuracy of ultrasound in detecting the presence of pus in a neck mass in children.
Design: Retrospective case sheet review.
Setting: A district general hospital.
Participants: Children admitted from January 2000 to January 2004 with an acute cervical mass who were investigated by ultrasonography.
Main outcome measures: The presence of a clinically relevant abscess that did not respond to clinical management was used to determine the accuracy of the ultrasound result.
Results: The sensitivity of ultrasound in the detection of an abscess was 65% and the specificity 88%. The predictive value of a positive ultrasound result was 81% and the predictive value of a negative test 77%.
Conclusions: Ultrasound is a useful modality in the evaluation of acute cervical masses but is observer dependent and has a relatively low sensitivity in detecting whether or not pus is present. The clinical indicators for the presence of an abscess are discussed and clinicians should combine clinical findings with the ultrasound findings in order to determine treatment.