Table 1.

Summary of publications with emphasis on secondary sonographic signs of appendicitis

Author	Year	Comments
Kessler et al.36	2004	Prospective study of 125 patients, not limited to children. There is examination of the diagnostic qualities of some secondary signs: inflammatory fat changes (SN 91%, SP 76%), caecal wall thickening (SN 25%, SP 88%), lymph nodes (SN 32%, SP 62%) and peritoneal fluid (SN 51%, SP 71%).
Lee et al.34	2009	Prospective study of 317 adult patients. Found that an increased intra‐abdominal fat echo was seen in patients with appendicitis (SN 73%, SP 98%).
Rodriguez et al.37	2006	Retrospective study of 769 children that underwent appendicectomy. Increased echogenic fat was seen more in children under 5 years (15%) compared to older children (4%).
Wiersma et al.3	2009	Prospective study of 212 children. Integrated secondary sonographic signs into their findings and found their absence to be a safe negative predictor without a visible appendix and a strong positive predictor of appendicitis when present (SN 99%, SP 97%, PPV 93%, NPV 99%).
Jaremko et al.38	2011	Retrospective study of 189 children integrating secondary sonographic signs into their findings and also identified that inconclusive ultrasounds were more likely in children older than 12 years (SN 88%, SP 89%, PPV 80%, NPV 93%).
van Atta et al.39	2014	Prospective study of 512 children using CT for equivocal cases and integrating secondary signs into their findings (SN 96%, SP 97%, PPV 94%, NPV 98%).

SN, sensitivity; SP, specificity; PPV, positive predictive value; NPV, negative predictive value; CT, computed tomography.