Morphological Variations of the Tracheobronchial Tree in the Paediatric Population: A Systematic Review With Meta-Analysis

Congenital variations of the tracheobronchial tree (TBT) represent deviations from the typical bronchial branching pattern established during early embryogenesis. Although individually uncommon, these anomalies are of considerable morphological and developmental interest, particularly in the paediatric population. Therefore, the purpose of the current systematic review is to depict meta-analytic evidence for paediatric patients. A systematic literature search was conducted across major databases to identify studies reporting congenital TBT morphological variations in paediatric populations. Eligible studies were evaluated according to predefined inclusion criteria. Pooled prevalence estimates were calculated using a random-effects meta-analysis. Twenty-six studies comprising 15,734 paediatric patients were included. The most prevalent anomaly was tracheal bronchus (TB), with a pooled prevalence of 13.41%, followed by accessory cardiac bronchus (ACB) (4.03%). Less frequent anomalies included bridging bronchus (1.43%), tracheal agenesis (0.86%), tracheal trifurcation (0.40%), and bronchial agenesis (0.13%). Substantial heterogeneity and asymmetry in the small-study effect were observed in the pooled prevalence estimates. Congenital variations of the TBT are more frequently identified in the paediatric population than previously recognized. TB and ACB constitute the most common morphological variants. Accurate anatomical characterization of these anomalies enhances understanding of airway development and supports their recognition in paediatric anatomical and imaging studies.