Comparison of sonographic findings between pediatric patients with mediastinitis and without mediastinitis after cardiovascular surgery

Purpose: To compare the sonographic findings between pediatric patients with/without mediastinitis after cardiovascular surgery. Methods: We included 18 pediatric patients with suspected mediastinitis after cardiovascular surgery who underwent ultrasound. They were divided into two groups according to the presence of mediastinitis, confirmed by positive bacterial culture from the mediastinum (number with/without mediastinitis = 5/13). The following sonographic findings were compared between the groups: (1) increased parasternal fat echogenicity and (2) retrosternal mediastinal fluid collection. Additionally, sex, age, and the interval between surgery and ultrasound examination were also compared. Fisher’s exact and Mann–Whitney U tests were used for statistical comparisons. Results: A significant difference was observed between patients with and without mediastinitis in the presence of increased fat echogenicity around the sternum (present/absent with mediastinitis vs. present/absent without mediastinitis: 5/0 vs. 3/10, respectively; P = 0.007) and retrosternal mediastinal fluid collection (5/0 vs. 2/11, respectively; P = 0.002). There was no significant difference in sex (male/female; 3/2 vs. 6/7; P > 0.999); age (months; 12.6 ± 9.4 (range, 1–22) vs. 6.9 ± 5.4 (range, 1–21); P = 0.336); and interval between surgery and ultrasound examination (days; 12.8 ± 7.2 (range, 6–20) vs. 19.1 ± 14.9 (range, 1–45); P = 0.443). Conclusion: Although our cohort was small, none of the patients without increased parasternal fat echogenicity or mediastinal fluid collection was diagnosed with mediastinitis. These sonographic findings may help identify the possible presence of mediastinitis. Ultrasound may be the modality of first choice to evaluate pediatric patients for mediastinitis after cardiovascular surgery.