title: Tracheo-bronchial angles in the human fetus -- an anatomical, digital, and statistical study.
abstract: BACKGROUND
  Both the advancement of visual techniques and intensive progress in perinatal medicine result in performing airway management in the fetus and neonate affected by life-threatening malformations. This study aimed to examine the 3 tracheo-bronchial angles, including the right and left bronchial angles, and the interbronchial angle, in the fetus at various gestational ages.
  
  
  METHODS
  Using methods of anatomical dissection, digital image analysis with an adequate program (NIS-Elements BR 3.0, Nikon), and statistics, values of the two bronchial angles and their sum as the interbronchial angle were semi-automatically measured in 73 human fetuses at the age of 14-25 weeks, derived from spontaneous abortions and stillbirths.
  
  
  RESULTS
  No male-female differences between the parameters studied were found. The 3 fetal tracheo-bronchial angles were found to be independent of age. The right bronchial angle ranged from 11.4° to 41.8°, and averaged 26.9±7.0° for the whole analyzed sample. The values of left bronchial angle varied from 24.8° to 64.8°, with the overall mean of 46.2±8.0°. As a consequence, the interbronchial angle totalled 36.2-96.6°, and averaged 73.1±12.7°.
  
  
  CONCLUSIONS
  The tracheo-bronchial angles change independently of sex and fetal age. The left bronchial angle is wider than the right one. Values of the 3 tracheo-bronchial angles are unpredictable since their regression curves of best fit with relation to fetal age cannot be modelled. Both of the 2 bronchial angles and the interbronchial angle are of great relevance in the location of inhaled foreign bodies, and in the diagnosis cardiac diseases and mediastinal abnormalities.
authors.affiliation: Department of Normal Anatomy, The Ludwik Rydygier Collegium Medicum in Bydgoszcz, The Nicolaus Copernicus University in Toruń, Bydgoszcz, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Daroszewski
authors.forename: Michał
authors.initials: M
authors.lastname: Szpinda
authors.forename: Piotr
authors.initials: P
authors.lastname: Flisiński
authors.forename: Anna
authors.initials: A
authors.lastname: Szpinda
authors.forename: Alina
authors.initials: A
authors.lastname: Woźniak
authors.forename: Adam
authors.initials: A
authors.lastname: Kosiński
authors.forename: Marek
authors.initials: M
authors.lastname: Grzybiak
authors.forename: Celestyna
authors.initials: C
authors.lastname: Mila-Kierzenkowska
mesh_terms: D001980:Bronchi / Q000033:anatomy & histology*; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D013223:Statistics as Topic; D014132:Trachea / Q000033:anatomy & histology*