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

BACKGROUND: 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. OBJECTIVE: To examine diagnostic performance of ultrasound for detecting perforated appendicitis in a single institution using a standardized technique. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Can ultrasound reliably identify complicated appendicitis in children?

BACKGROUND: The ability of ultrasound to identify specific features relevant to nonoperative management of pediatric appendicitis, such as the presence of complicated appendicitis (CA) or an appendicolith, is unknown. Our objective was to determine the reliability of ultrasound in identifying these features. METHODS: We performed a retrospective study of children who underwent appendectomy after an ultrasound at four children's hospitals. Imaging, operative, and pathology reports were reviewed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ultrasound for identifying CA based on pathology and intraoperative findings and an appendicolith based on pathology were calculated. CA was defined as a perforation of the appendix. Equivocal ultrasounds were considered as not indicating CA. RESULTS: Of 1027 patients, 77.5% had simple appendicitis, 16.2% had CA, 5.4% had no evidence of appendicitis, and 15.6% had an appendicolith. Sensitivity and specificity of ultrasound for detecting CA based on pathology were 42.2% and 90.4%; the PPV and NPV were 45.8% and 89.0%, respectively. Sensitivity and specificity of ultrasound for detecting CA based on intraoperative findings were 37.3% and 92.7%; the PPV and NPV were 63.4% and 81.4%, respectively. Sensitivity and specificity of ultrasound for detecting an appendicolith based on pathology were 58.1% and 78.3%; the PPV and NPV were 33.1% and 91.0%, respectively. Results were similar when equivocal ultrasound and negative appendectomies were excluded. CONCLUSIONS: The high specificity and NPV suggest that ultrasound is a reliable test to exclude CA and an appendicolith in patients being considered for nonoperative management of simple appendicitis.