Table 1.

Previously reported anatomical variations of the bronchi in the right upper lobe

	Right upper lobe	Inspection method	Author, Year
Normal findings and most common bronchial variations	Trifurcation B1, B2, B3	3DCT; Bronchography	Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]
	Bifurcation B1 + 2, B3	3DCT; Bronchography	Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]
	Bifurcation B1 + 3, B2	3DCT; Bronchography	Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]
	Bifurcation B2 + 3, B1	3DCT; Bronchography	Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]
	Bifurcation B1a + 2, B1b + 3	3DCT; Bronchography	Nagashima et al. (2015) [3]; Zhang et al. (2021) [9]
	Bifurcation B1 + 2a, B2b + 3	3DCT; Bronchography	Nagashima et al. (2015) [3]; Zhang et al. (2022) [10]
	Quadrifurcation	3DCT; Bronchography	Nagashima et al. (2015) [3]; Gonlugur et al. (2005) [8]
Rare variations	Tracheal bronchus	Thoracoscopy; Bronchography	Yurugi et al. (2012) [11]; Martín-Ruiz et al. (2021) [4]
	Right upper lobe bronchus ectopic to the intermediate bronchus	3DCT	Huang et al. (2020) [5]
	B1 ectopic to the lateral wall of the trachea or the right main bronchus (Right B1 Type))	CT	Yaginuma (2020) [7]
	B2 ectopic to the intermediate bronchus (Right B2 Type)	CT	Yaginuma (2020) [7]
	B3 ectopic to the intermediate bronchus (Right B3 Type)	3DCT	Ghaye et al. (2001) [6]; Yaginuma (2020) [7]

B¹ = apical segmental bronchus; B² = posterior segmental bronchus; B³ = anterior segmental bronchus; 3DCT = three-dimensional computed tomography; CT = computed tomography