The utility of sonographic signs to diagnose simple and complicated appendicitis in children

BACKGROUND: Acute appendicitis is classified into simple (SA) and complicated (CA). Ultrasound scans (USS) can be useful in clinically equivocal cases, by visualising primary and secondary signs. This study explores the utility of sonographic signs to diagnose and differentiate appendicitis in children. METHODS: Single-centre retrospective cohort study over a 2-year period. Consecutive USS for suspected appendicitis were included; sonographic signs were extracted from standardised institutional worksheets. USS results were compared with pre-defined intraoperative criteria for SA and CA, confirmed with histological analysis. Data are reported as median [interquartile range], percentages (number), area under the curve (AUC), conventional diagnostic formulae and adjusted odds ratios following multiple logistic regression (p < 0.05 considered significant). RESULTS: A total of 934 USS were included, with median age 10.7 [8.0–13.4] years, majority were female (54%). One quarter (n = 226) had SA, 12% (n = 113) had CA, 61% (n = 571) had no appendectomy and 3% (n = 24) had negative appendicectomy. Appendix visualisation rate on USS was 61% (n = 569), with 62% (n = 580) having a conclusive report. Sonographic signs suggesting appendicitis included an appendiceal diameter > 7 mm (AUC 0.92, [95% CI: 0.90–0.94]), an appendicolith (p = 0.003), hyperaemia (p = 0.001), non-compressibility (p = 0.029) and no luminal gas (p = 0.004). Secondary sonographic signs included probe tenderness (p < 0.001) and peri-appendiceal echogenic fat (p < 0.001). Sonographic signs suggesting CA over SA comprised a diameter > 10.1 mm (AUC 0.63, [95% CI: 0.57–0.69]), an appendicolith (p = 0.003) and peri-appendiceal fluid (p = 0.004). CONCLUSION: Presence of specific sonographic signs can aid diagnosis and differentiation of simple and complicated appendicitis in children. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00383-023-05397-y.