Background: : Surgical site infections (SSI) are a frequent and significant problem understudied in infants operated for abdominal birth defects. Different forms of SSIs exist, namely wound infection, wound dehiscence, anastomotic leakage, post-operative peritonitis and fistula development. These complications can extend hospital stay, surge medical costs and increase mortality. If the incidence was known, it would provide context for clinical decision making and aid future research. Therefore, this review aims to aggregate the available literature on the incidence of different SSIs forms in infants who needed surgery for abdominal birth defects. Method: : The electronic databases Pubmed, EMBASE, and Cochrane library were searched in February 2020. Studies describing infectious complications in infants (under three years of age) were considered eligible. Primary outcome was the incidence of SSIs in infants. SSIs were categorized in wound infection, wound dehiscence, anastomotic leakage, postoperative peritonitis, and fistula development. Secondary outcome was the incidence of different forms of SSIs depending on the type of birth defect. Meta-analysis was performed pooling reported incidences in total and per birth defect separately. Results: : 154 studies, representing 11,786 patients were included. The overall pooled percentage of wound infections after abdominal birth defect surgery was 6% (95%-

Purpose Accurate differentiation between simple and complex appendicitis is important since differences in treatment exist. This study aimed to assess the accuracy of ultrasonography in differentiating between simple and complex appendicitis. Methods Data from children aged < 18 years who underwent appendectomy between the 1st of January 2013 and the 1st of January 2018 were analyzed retrospectively. Ultrasonography reports of eligible children were divided into simple (test negative) and complex appendicitis (test positive) based on predefined criteria and compared to a gold standard (a combination of predefined perioperative and histopathological criteria). Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated to measure ultrasonographic accuracy in differentiating between simple and complex appendicitis. Results 176 children were eligible for inclusion. The mean age at the time of operation was 10.1 ± SD 4.6 years. 84 (47.7%) children had simple appendicitis and 92 (52.3%) had complex appendicitis. The use of ultrasonography yielded a sensitivity: 46%, specificity: 90%, PPV: 84%, and NPV: 60%. Conclusion Ultrasonography as standalone modality is not suitable for differentiating between simple and complex appendicitis in children. To improve preoperative differentiation, other variables such as clinical signs and laboratory data are necessary in conjunction with ultrasonography findings.