“…Three different classifications were used to characterize the type of major BDI: The Strasberg classification, the Bismuth classification, and the Stewart Way System. Fifteen studies, accounting for 49% ( n = 2440)[ 26 , 33 , 34 , 36 - 43 , 45 - 47 , 49 , 50 ] of BDIs, used the Strasberg classification system, three studies, including 8% ( n = 395)[ 43 , 47 , 51 ] of BDIs, used the Bismuth classification, and one study, reporting 6% ( n = 307)[ 18 ] of BDIs, used the Stewart Way System (Table 2 ) . Five studies, including 36% ( n = 17924)[ 25 , 27 , 28 , 35 , 49 ] of patients, did not identify which classification system was used.…”