Abstract
Imaging modalities are not included in The European League Against Rheumatism, The Pediatric Rheumatology International Trials Organization and The Pediatric Rheumatology European Society 2010 criteria for the evaluation of abdominal purpura. The objective of the present study was to compare diagnostic parameters of ultrasound, X-ray and computed tomography (CT) for diagnosis of abdominal purpura considering the American College of Rheumatology (ACR) criteria as 'reference standard' in children with acute abdominal pain. Medical records of 215 children with acute abdominal pain were reviewed. Data regarding demographics and clinical characteristics, laboratory tests, X-ray, ultrasound findings, and computed tomographic images were collected and analyzed. Decision curve analysis was used for evaluation of the beneficial score for each diagnostic modality. Among diagnostic modalities, CT had the highest sensitivity (0.939); however, ultrasound findings had the highest accuracy (0.861) for diagnosis of abdominal purpura. Unlike X-ray and laboratory tests, ultrasound and CT were successful at detecting abdominal purpura when children had only colicky pain and were aged <20 years; however, occult blood stool test and granulocytes in the walls of small venules and arterioles (biopsy results) were negative. With respect to the ACR criteria, there were seven and three inconclusive results for ultrasound and CT, respectively. Abdominal ultrasound is an easy, non-invasive and safe method for the detection of abdominal purpura in children.