D. O. Gonzalez1, A. Lawrence1, J. Cooper1, R. Sola2, E. Garvey3, B. C. Weber4, S. D. St. Peter2, D. J. Ostlie3, J. E. Kohler4, C. M. Leys4, K. J. Deans1, P. C. Minneci1 1Nationwide Children’s Hospital,Columbus, OH, USA 2Children’s Mercy Hospital- University Of Missouri Kansas City,Kansas City, MO, USA 3Phoenix Children’s Hospital,Phoenix, AZ, USA 4American Family Children’s Hospital,Madison, WI, USA
Introduction: Although ultrasound is commonly used to diagnose pediatric appendicitis, its ability to identify specific features relevant to non-operative management, such as the presence of complicated appendicitis (CA) or an appendicolith, are unknown. The objective of this study was to determine the reliability of ultrasound in identifying these features.
Methods: We performed a multi-institutional retrospective study of patients aged 2-18 years who underwent appendectomy after an abdominal ultrasound during 2015 at four children’s hospitals. Interval and incidental appendectomies were excluded. Charts were reviewed for patient characteristics and imaging, operative, and pathology reports. All cases were classified as either CA or simple appendicitis (SA) based on pathology and operative findings. CA was defined as appendicitis with a perforation of the appendix or extraluminal appendicoliths/enteric contents; SA was defined as a hyperemic or inflamed/gangrenous appendix without perforation. Two separate analyses of the diagnostic parameters of ultrasound were performed. First, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ultrasound for identifying CA were calculated. In these analyses, equivocal ultrasounds were considered as not indicating CA. Second, the sensitivity, specificity, PPV, and NPV of ultrasound for identifying the presence of an appendicolith (ether intra- or extraluminal) were calculated.
Results: 1027 patients were included. Based on pathology, 77.5% had SA, 16.2% had CA, 5.4% had no evidence of appendicitis, and 15.6% had an appendicolith. The 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%. The sensitivity and specificity of ultrasound for detecting CA based on intra-operative findings were 37.3% and 92.7%; the PPV and NPV were 63.4% and 81.4%. The 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%. Results were similar when equivocal ultrasounds and negative appendectomies were excluded.
Conclusion: Despite the low sensitivity of ultrasound for diagnosing CA or an appendicolith, the high specificity and NPV suggest that ultrasound is a reliable test to exclude CA and an appendicolith in patients being considered for non-operative management of SA.