Patent ID: 8366606

Claim:
A method for inserting an endoscope into a colon, the endoscope comprising: an insertion portion having a tip end side portion and a rear end side portion, the insertion portion comprising: a flexible tube portion provided at the rear end side portion of the insertion portion, a first bendable section selectively bent in a bending direction operated by a bending direction operation section, the first bendable section being provided at the tip end side portion of the insertion portion and formed by rotatably connecting a plurality of bending pieces along a longitudinal direction of the insertion portion, a second bendable section provided between the flexible tube portion and the first bendable section, and formed by rotatably connecting a plurality of bending pieces along the longitudinal direction of the insertion portion, and hardness varying means for varying the hardness of the second bendable section relative to the hardness of the flexible tube portion and the first bendable section, the hardness varying means including: a balloon tube having at a tip end thereof an inflatable balloon, and a tube into which the balloon tube is inserted such that the balloon is located within a range where the second bendable section is provided, the tube being provided in the longitudinal direction of the insertion portion, and a tip end of the tube being fixed, in a closed state, to the tip end side portion of the insertion portion, and a base fixing section provided in a vicinity of a base end of the endoscope, and detachably connected to a fluid supply device for supplying a fluid, the base fixing section fixing a rear end of the balloon tube in an open state inside a rear end of the tube, the method comprising steps of: causing the first bendable section to reach a descending colon; increasing the hardness of only the second bendable section relative to the hardness of the flexible tube portion and the first bendable section by supplying the fluid from the fluid supply device to the balloon; and making a sigmoid colon portion straight by twisting and pulling the insertion portion after the hardness of only the second bendable section is increased and inserting the insertion portion into the colon.