Oblique tip endoscope with zero degree field angle

An endoscopic sheath comprising:

• an elongated shaft that defines a central axis, a proximal end, and a distal tip, the elongated shaft defines a cross-section;
• a first portion of the distal tip defines a first plane that forms an angle of between and including 20 and 45 degrees to the central axis;
• a second portion of the distal tip defines a second plane that is perpendicular to the central axis;
• a first transition area on a first side of the distal tip between the first portion and the second portion, the first transition area varying between the first portion and the second portion;
• a second transition area on a second side of the distal tip opposite the first side, the second transition area varying between first portion and the second portion;
• at least one aperture disposed at a distal end of the elongated shaft proximate to the first portion;
• and
• an insertion port at the proximal end of the elongated shaft.

An endoscope and sheath system comprising:

• an endoscope comprising:
• an endoscope elongated shaft that defines an endoscope central axis, an endoscope proximal end, and an endoscope distal tip, the endoscope elongated shaft defines a cross-section;
• an endoscope first portion of the endoscope distal tip defines a first plane that forms an angle of between and including 20 and 40 degrees to the endoscope central axis;
• an endoscope second portion of the endoscope distal tip defines a second plane that is perpendicular to the endoscope central axis;
• an endoscope first transition area on a first side of the endoscope distal tip between the endoscope first portion and the endoscope second portion, the endoscope first transition area varying between the endoscope first portion and the endoscope second portion;
• an endoscope second transition area on a second side of the endoscope distal tip opposite the first side, the endoscope second transition area varying between the endoscope first portion and the endoscope second portion;
• a first channel within the endoscope elongated shaft that terminates at the endoscope first portion;
• a second channel within the endoscope elongated shaft that terminates at the endoscope second portion, the second channel fluidly isolated from the first channel along a length of the endoscope elongated shaft;
• and
• a visualization conduit that extends through the second channel, the visualization conduit optically exposed at the second plane such that a viewing angle through the visualization conduit is parallel to the endoscope central axis;
• a sheath comprising:
• a sheath elongated shaft that defines a sheath central axis, a sheath proximal end, and a sheath distal tip, the sheath elongated shaft defines a cross-section;
• a sheath first portion of the sheath distal tip defines a third plane parallel to the first plane;
• a sheath second portion of the sheath distal tip defines a fourth plane parallel to the second plane;
• a sheath first transition area on a first side of the sheath distal tip between the sheath first portion and the sheath second portion, the sheath first transition area varying between the sheath first portion and the sheath second portion;
• a sheath second transition area on a second side of the sheath distal tip opposite the first side, the sheath second transition area varying between sheath first portion and the sheath second portion;
• at least one aperture disposed a sheath distal end of the sheath elongated shaft proximate to the sheath first portion;
• and
• an insertion port at the sheath proximal end of the sheath elongated shaft, the endoscope elongated shaft telescoped through the sheath insertion port.

A method comprising:

• positioning a distal tip of an endoscope to abut an aperture into a patient's body, a distal tip of the endoscope having a first portion that defines a first plane that forms an angle between and including 20 and 40 degrees with a central axis of the endoscope, and a second feature that defines a second plane perpendicular to the central axis of the endoscope;
• inserting the distal tip of the endoscope through the aperture into the patient's body;
• and
• visualizing an interior portion of the patient's body at a viewing angle that is parallel to the central axis.

A method comprising:

• assembling an endoscope by:
• obtaining an outer tube that comprises:
• a first central axis, a first proximal end, and a first distal tip;
• a first portion at the first distal tip defines a first plane that forms an angle of between and including 20 and 40 degrees to the first central axis;
• and
• a second portion at the first distal tip that defines a second plane perpendicular to the first central axis;
• obtaining an inner tube that comprise:
• a second central axis, a second proximal end, and a second distal tip;
• a first portion at the second distal tip defines a third plane that forms an angle of between and including 20 and 40 degrees to the second central axis;
• and
• a second portion at the second distal tip that defines a fourth plane perpendicular to the second central axis;
• telescoping the inner tube into the outer tube until the first and third planes are coplanar and two channels are defined within the outer tube, the first channel within the inner tube, and the second channel defined between the inner tube and an inside surface of the outer tube;
• telescoping within the second channel a visualization conduit;
• and
• optically exposing the visualization conduit at the first distal end with viewing angle parallel to the first central axis.