Surgical treatment device

1. A biotissue excision instrument comprising:

an elongated sheath having an outer peripheral wall defining an inner cavity therein, and a slit formed in the outer peripheral wall,

a loop wire which is inserted in the inner cavity and extending in an elongated direction of the sheath, the loop wire having two elongated portions and a tip bent portion which connects the elongated portions to each other, the elongated portions having separated distal end portions;

an engaging member which detachably engages the tip bent portion of the loop wire to the sheath; and

a manipulating member which is connected to the distal end of one of the elongated portions, and advances said one of the elongated portions to outwardly project a section of said one of the elongated portion in a loop shape through the slit when said tip bent portion of the loop wire is engaged with the engaging member, so that the loop shape section of the wire outwardly extended from the slit encloses a biotissue.

2. A biotissue excision instrument according to claim 1 , wherein said distal ends of the elongated portions are positioned in the inner cavity when the tip bent portion of the loop wire is engaged with the sheath.

3. A biotissue excision instrument according to claim 2 , further comprising a slider which is slidably inserted in the inner cavity and to which the distal end of the other elongated portion is fixed, said one elongated portion being movable against the slider.

4. A biotissue excising instrument comprising:

a loop member having a bent portion;

a manipulation member for operating the loop member so that the loop member excises a biotissue; and

a sheath having a distal end portion and a proximal end portion, the distal end portion having a cavity therein in which the loop member is received, the sheath having a slit formed in a side thereof, the slit being communicated with the cavity,

the cavity of the sheath having an engaging portion which is detachably engaged with the bent portion by elastic deformation of the bent portion,

the loop member being positioned in the cavity to be outwardly extendable through the slit in accordance with an operation of the manipulation member;

wherein said loop member has a closed loop portion formed by at least one wire, the closed loop portion is outwardly extendable from the slit.

5. A biotissue excising instrument according to claim 4 , wherein said engaging portion is formed by reducing an inner diameter of the cavity, and the bent portion is inserted into the engaging portion and engaged thereto by a deformation of the bent portion.

6. A biotissue excising instrument according to claim 4 , wherein a shoulder portion is formed at the leading end of the loop portion and abuts against a leading edge of the slit when the manipulation member is advanced toward the leading end of the sheath.

7. A biotissue excising instrument according to claim 6 , wherein the inner diameter of area of the sheath which forms the slit is set to be equal to or larger than the length of area of the loop portion which projects toward the leading end beyond the shoulder portion.

8. A biotissue excising instrument according to claim 4 , wherein the loop portion is formed of a solid wire.

9. A biotissue excising instrument according to claim 4 , wherein the cavity of said sheath is formed to extend in an elongated direction of the sheath, the cavity having distal end side and a proximal end side, and said engaging portion is positioned on the distal end side of the cavity.

10. A biotissue excising instrument according to claim 9 , wherein said bent portion has a guide for guiding the bent portion to the engaging portion.

11. A biotissue excising instrument according to claim 4 , further comprising a slider provided so as to move freely toward to the proximal end portion of the sheath to advance and retreat the manipulation member,

wherein when the slider is located at a leading end of its moving path, the loop portion is unfolded maximally, and when the slider is located at a proximal end of its movement path, the loop portion sinks completely in an area of the sheath which is closer to the proximal end than the slit.

12. A biotissue excising instrument according to claim 4 , further comprising a collar member arranged in the sheath to extend from a proximal edge of the slit toward the proximal end of the sheath by a predetermined length.

13. A biotissue excising instrument according to claim 12 , wherein the collar member is formed to reinforce the sheath and prevent biotissue from entering the sheath.

14. A biotissue excising instrument according to claim 12 , wherein the collar member has an extending portion extending from the proximal edge of the slit toward the leading end of the sheath by a predetermined length.

15. A biotissue excising instrument according to claim 4 , further comprising an opening direction varying mechanism to vary the direction in which an opening surface of the loop portion is opened.

16. A biotissue excising instrument according to claim 15 , wherein the opening direction varying mechanism is comprised of a tube fitted around an outer periphery of the sheath so as to advance and retreat freely, the tube having a leading end surface abutting against the loop portion projecting out of the slit to change the direction in which the loop portion projects.

17. A biotissue excising instrument according to claim 15 , wherein the opening direction varying mechanism is comprised of a tube fitted around an outer periphery of the sheath so as to advance and retreat freely, the tube having at least one opening which is placed opposite the slit in the sheath from different directions depending on the amount by which the tube is moved relative to the sheath.

18. A biotissue excising instrument according to claim 1 , further comprising a tube slidably fitted around an outer periphery of the sheath to close an opening of the slit.

19. A biotissue excising instrument according to claim 1 , wherein the sheath has a holding portion which holds the loop portion substantially within one surface at the leading and proximal ends of the slit.

20. A biotissue excising instrument according to claim 15 , wherein the loop portion is comprised of a first wire portion and a second wire portion which is harder than the first wire portion and which has a larger outer diameter than the first wire portion, and the loop portion is unfolded by projecting the first wire portion out of the slit, and

wherein the first wire portion is provided with a tendency to bend in such a direction as resists twist of the loop portion.

21. A biotissue excision instrument according to claim 4 , wherein said bent portion is deformable and elastically engaged with the engaging portion.