Endoscope sheath, endoscope arrangement, and method for providing an endoscope arrangement

1. A method for providing an endoscope arrangement, wherein a flexible endoscope, a flexible endoscopic working instrument and an endoscope sheath are provided, wherein the endoscope sheath comprises an elongate flexible hose which encloses a main lumen, for receiving at least one portion of a shank of the flexible endoscope, and at least one working channel, extending parallel to the main lumen and receiving at least one portion of the flexible endoscopic working instrument, and wherein the endoscope sheath has a transparent distal end portion, wherein furthermore at least one portion of the shank of the flexible endoscope is inserted into the main lumen such that a viewing lens of the endoscope is arranged in a distal end area of the endoscope sheath, the distal end area of the endoscope sheath is rotated relative to a proximal end area about a central longitudinal axis of the main lumen, such that the working channel extends helically around the central longitudinal axis of the main lumen, the endoscope sheath is fixed in rotation relative to the endoscope in a proximal and a distal end area, and wherein at least one portion of the flexible endoscopic working instrument is inserted into the working channel.