Diagnostic performance of standardized ultrasound protocol for detecting perforation in pediatric appendicitis

Recent clinical trials in adults and children have shown that uncomplicated acute appendicitis can be successfully treated with antibiotics alone. As treatment strategies for acute appendicitis diverge, accurate preoperative diagnosis of complicated appendicitis and appendiceal perforation has become increasingly important for clinical decision-making.

To examine diagnostic performance of ultrasound for detecting perforated appendicitis in a single institution using a standardized technique.

In this retrospective single-center study we evaluated 113 ultrasounds from pediatric patients who underwent appendectomy between November 2014 and December 2015. All ultrasounds were performed using a standardized US protocol including still and cine images of all four abdominal quadrants, with more targeted evaluation of the right lower quadrant (RLQ) using graded compression technique. We compared US findings to intraoperative diagnosis of non-perforated or perforated acute appendicitis.

The standardized image protocol generated a reproducible set of ultrasound images in all cases. The most common primary appendiceal finding on US in perforated appendicitis was appendix wall thickening >3 mm (54%, 171/314) and most common secondary finding was echogenic mesenteric fat (75%, 237/314). Thinning of the appendix wall and loculated fluid collection in the right lower quadrant were both highly specific (>90%) for perforation.

The diagnostic performance of ultrasound using a standardized US technique was similar to that reported in prior studies for detecting perforated appendicitis. Despite low sensitivity, individual ultrasound findings and overall diagnostic impression of "evidence of appendix perforation" remain highly specific.