What is the most probable diagnosis for an infant with a tracheoesophageal fistula presenting with expiratory stridor and wheezing at 5 months old?

In the context of an infant with a tracheoesophageal fistula (TEF) exhibiting expiratory stridor and wheezing at 5 months old, the most probable diagnosis is tracheomalacia. This condition is characterized by the weakness of the tracheal walls, leading to collapse during expiration, which can cause stridor—a high-pitched wheezing sound as the airway narrows—and wheezing due to turbulent airflow.

Tracheoesophageal fistulas can lead to complications such as tracheomalacia because the abnormal connection between the esophagus and trachea can result in recurrent aspiration, inflammation, and changes in tracheal support. Therefore, the symptoms of stridor and wheezing strongly suggest a functional issue with the trachea itself, consistent with tracheomalacia.

Other choices could be considered but are less likely in this scenario. Reactive airway disease typically presents with wheezing and may be linked to previous respiratory infections or allergies, but it is less common to present primarily with stridor in the context of TEF. Foreign body aspiration could cause similar symptoms but is less likely in a controlled clinical scenario without additional context suggesting acute emergency signs. Aspiration pneumonia would generally present with respiratory distress and possibly fever, and may