 1. PTBD procedure 17 Either a right or left sided approach will be used for PTBD. Once entry will be gained to a suitable duct the standard Seldinger technique will be used to place a guidewire in the biliary system. The tract will be dilated and after crossing the obstruction with a hydrophilic guidewire, a ring biliary catheter will be placed to provide internal-external drainage. In a subsequent session, a 10 F, straight plastic stent polyurethane will be placed into the system across the obstruction to provide internal drainage. 