Table 1. The characteristics of the stone and procedure-related factors.

	N = 169
PTBD tube size
7fr	10 (5.9%)
8.5fr	159 (94.1%)
PTBD site
Lt.	32 (18.9%)
Rt.	137 (81.1%)
Previous EST
no	137 (81.1%)
yes	32 (18.9%)
Number of stones	1.0 [1.0;2.0]
Long diameter of largest stone (mm)	16.1 [11.7;21.8]
Short diameter of largest stone (mm)	11.7 [8.3;15.9]
Volume of largest stone (mm3)	8973.1 [3321.8;21387.8]

Data shown are number (%), or median [IQR; interquartile range].

PTBD = percutaneous transhepatic biliary drainage; EST = endoscopic sphincterotomy.