title: Tracheal bronchus in the adult population.
abstract: BACKGROUND
  Tracheal bronchus is an abnormal bronchus that comes directly off the lateral wall of the trachea (ie, above the main carina) and supplies ventilation to the upper lobe. A new nomenclature and classification system has been developed for tracheal bronchus. The purpose of this study was to evaluate the anatomic and bronchoscopic features of tracheal bronchus subtypes on the basis of the new nomenclature and classification system.
  
  
  METHODS
  A retrospective study was performed using data from eight patients with tracheal bronchus.
  
  
  RESULTS
  The incidence of tracheal bronchus was found to be 0.06% (8 of 12,648 patients) and the distribution of the subtypes was as follows: displaced type (7 patients, 87.5%) and supernumerary type (1 patient, 12.5%). Among the patients with displaced tracheal bronchus, 6 had displaced preeparterial (75%), 1 had displaced preeparterial and posteparterial tracheal bronchus (12.5%), and 1 patient had supernumerary eparterial tracheal bronchus (12.5%). In all cases, the tracheal bronchi were located on the right side of the trachea. The mean distance between the origin of the tracheal bronchus and main carina was 16.25 mm (range, 5 to 40 mm). In 1 case, posteparterial bronchus was detected with its orifice on the lateral side of the intermediate bronchus.
  
  
  CONCLUSIONS
  Displaced preeparterial tracheal bronchus was the most common subtype of tracheal bronchus. Furthermore, in all cases, tracheal bronchus was located on the right side of the trachea. Both flexible bronchoscopy and computed tomography of the chest were crucial for its diagnosis.
authors.affiliation: Department of Pulmonary Medicine, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey. serhatfindik1@yahoo.com
authors.forename: Serhat
authors.initials: S
authors.lastname: Findik