Fig. 3a　After we began using 28-Fr diameter drainage tubes, we were able to insert a standard peroral endoscope （GIF-Q260, Olympus, Japan, diameter: 9.2 mm）.

Fig. 3b　We successfully removed a large portion of necrotic tissue using grasping forceps（FG-8L-1 and FG-45L-1, Olympus, Japan）, a retrieval net （Roth Net -foreign body- standard, Olympus, Japan）, and other instruments.