Outflow system for an endoscope

A method of constructing a medical instrument comprising:

• providing an inner sheath and outer sheath and assembling the two such that for at least a portion of an inner sheath, an outflow channel is disposed between the inner sheath and outer sheath, the assembly having an outflow conduit with an outflow aperture initiating in an outer wall at the distal end of the assembly, the conduit being disposed generally in a longitudinal direction and communicating with the outflow channel formed between the outer sheath and inner sheath so that fluid may be directed from the outflow conduit into the outflow channel;
• wherein the outflow conduit initiates in a distal tip portion of the sheath assembly in a position distal to a main inflow hole for the sheath assembly;
• and
• wherein the tip portion comprises a dielectrical tip element disposed at the distal end of the outer sheath, the tip element having a plurality of lateral outflow openings, the openings being in fluid communication with a channel between the inner and outer sheaths.

A method of using a medical instrument in a surgical procedure comprising, inserting into a surgical site of a patient an assembly of an outer sheath and inner sheath for providing inflow and outflow of fluids at a surgical site, the outer sheath is disposed about at least a portion of the inner sheath, and an outflow channel is disposed between the inner sheath and outer sheath, the assembly having an outflow conduit with an outflow aperture initiating in an outer wall at the distal end of the assembly, the conduit is disposed generally in a longitudinal direction and communicates with the outflow channel formed between the outer sheath and inner sheath so that fluid may be directed into the outflow channel from the outflow conduit;

• and, withdrawing fluid through the outflow channel via the outflow conduit and associated outflow aperture;
• wherein the outflow conduit initiates in a distal tip portion of the sheath assembly in a position distal to a main inflow hole for the sheath assembly;
• and
• wherein the tip portion comprises a dielectrical tip element disposed at the distal end of the outer sheath, the tip element having a plurality of lateral outflow openings, the openings being in fluid communicating with a channel between the inner and outer sheaths.