Saber sheath trachea is a radiological term used to describe a
specific narrowing and deformity of the trachea, where the tracheal
walls appear to be flattened laterally (side-to-side) but widened
anteriorly and posteriorly (front-to-back). This condition is
commonly associated with chronic obstructive pulmonary disease
(COPD), particularly in long-term smokers. The pathogenesis
involves chronic inflammation and structural changes in the
tracheal cartilage, leading to a reduction in its lateral diameter and
giving it a “saber sheath” appearance on imaging. On imaging, the
lateral diameter of the trachea is often less than 2/3 of the
anteroposterior diameter, confirming the diagnosis. Although saber
sheath trachea is often asymptomatic, it can indicate chronic
changes related to long-standing lung disease and may be
considered when evaluating patients with COPD or other
obstructive airway conditions.