1. Field of the Invention
The present invention relates to an endoscope having an insertion portion provided with a first and a second bendable sections and a method for inserting the endoscope into a colon.
2. Description of the Related Art
An endoscope in the medical field can be used by inserting an elongated insertion portion into a body cavity for observation of organs and the like in the body cavity or performing various treatments using a treatment instrument inserted into a treatment instrument insertion channel as necessary. In this endoscope insertion portion, a tip end (constituting) portion, a bendable section and a flexible tube portion in order from the tip end are disposed.
When the insertion portion of the endoscope is to be inserted into a body cavity, an operator grips the flexible tube portion and operates an operation knob disposed at an operation portion of the endoscope by a predetermined amount so as to bend the bendable section in a desired direction while pushing it into the body cavity. This type of insertion portion of the endoscope has various improvements to reinforce insertion ability into a curved body cavity.
For example, in the insertion portion of the endoscope described in Japanese Utility Model Publication No. 1-22641, a first bendable section which can be actively operated from outside to be bent in four directions and a second bendable section which is provided with a stay coil and a joint ring and is very easily bent and in a structure passively bent in four directions are provided consecutively in order from the tip end side.
Also, Japanese Unexamined Patent Application Publication No. 2002-143084 discloses an endoscope provided with a first bendable section and a second bendable section with hardness larger than that of the first bendable section.