Normal tracheal bifurcation angle: a reassessment.

The tracheal bifurcation angle was measured in 100 normal adult patients. A wide range of normal values was found. There was no relation of the bifurcation angle to age or gender. There was only a weak correlation between bifurcation angle and height or width or the thorax. Thus, absolute measurements of the tracheal bifurcation angles are of little diagnostic value. In addition, when the angle was measured on two successive films, large changes (greater than 20%) were noted about 20% of patients.