Follow-up ultrasonographic findings among children treated conservatively for uncomplicated acute appendicitis

BACKGROUND: Ultrasound is an accurate tool for diagnosing acute appendicitis. Conservative treatment for uncomplicated acute appendicitis is feasible and safe in children. However, no sonographic follow-up results from children with nonoperatively managed acute appendicitis have been reported. OBJECTIVE: To describe the sonographic appearance of the appendix at follow-up ultrasound and to attempt to identify signs predictive of recurrent acute appendicitis. MATERIALS AND METHODS: Children diagnosed with uncomplicated acute appendicitis and treated conservatively in our hospital from 2014 to 2019, and who presented for follow-up ultrasound at 3, 6 and 9 months, were included in our study. Clinical, laboratory and ultrasound data were recorded. RESULTS: By the end of follow-up, 29 (14.2%) of 204 children in the cohort had developed recurrent acute appendicitis and 175 had recovered uneventfully. On follow-up ultrasound, appendiceal diameter measured > 6 mm in 56/204 (27.5%) cases at 3 months and in 9/26 (34.5%) at 6 months. After 3 months, 102/204 (50%) children had normal appendiceal diameter on ultrasound. Appendiceal diameter > 6 mm was associated with intraluminal fluid or sludge in the appendiceal lumen at 3- and 6-month follow-up (P < 0.001, P = 0.002, respectively). Comparing cases with and without recurrence, at 3-month follow-up, appendiceal diameter > 6 mm was found in 17/29 (58.6%) cases vs. 39/175 (22.3%), respectively (P < 0.001). Appendiceal diameter returned to normal in 12/19 (63.2%) cases in the nonrecurrent acute appendicitis group compared with 2/7 (28.6%) in the recurrent acute appendicitis group (P = 0.05) at the 6-month follow-up. Intraluminal fluid or sludge was detected more frequently in the recurrent acute appendicitis versus the nonrecurrent acute appendicitis group at 3- (P < 0.001) and 6-month (P = 0.001) follow-up. CONCLUSION: Progressive normalization of appendiceal diameter was noted on follow-up ultrasound. The prevalence of both appendiceal diameter > 6 mm and intraluminal fluid or sludge were found to be increased in children who later developed recurrent acute appendicitis. Ultrasound appears to be a useful tool for follow-up in children with conservatively treated uncomplicated acute appendicitis and possibly might help predict recurrence. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00247-022-05497-2.