Severity grading systems for complications in surgical patients have been used since 1992. An increasing assessment of these instruments in pediatric surgery is also noticed, without their validation in children. To analyze the current practice, we performed a literature review with focus on the assessment and grading of complications. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies reporting on postoperative complications as a primary or secondary endpoint using a severity grading system were included. Definition for simple adverse events, classification systems used, and the time horizon of postoperative documentation were analyzed. A total of 566 articles were screened, of which 36 met the inclusion criteria. About 86.1% of the papers were retrospective and 13.9% prospective analyses. None of the studies were prospective-randomized trials. Twenty (55.6%) studies did not include a definition of adverse events, whereas the remaining 16 (44.4%) showed variations in their definitions. All studies applied the Clavien-Dindo classification, whereas five (13.9%) additionally used the Comprehensive Complication Index. One study compared alternative grading instruments with the Clavien-Dindo classification, without demonstrating the superiority of any classification in pediatric surgery. Twenty-two studies (61.1%) did not report the time horizon of perioperative complication documentation, while 8 studies (22.2%) used 30 days and 6 studies (16.7%) used 3 months of postoperative documentation. Definition and classification of postoperative complications are inconsistent in the pediatric surgical literature. Establishment of a standardized protocol is mandatory to accurately compare outcome data.