Abstract:
Endoscopic biopsy forceps that allows a non-deformed, high-quality tissue specimen to be readily collected from the correct target position. Needles that extend forward to project into a pair of forceps cups are offset from the center of said pair of forceps cups.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to endoscopic biopsy forceps that is passed through the forceps channel in an endoscope to collect a tissue specimen for biopsy from within a body cavity. 
     Endoscopic biopsy forceps generally comprise a sheath to be inserted into or removed from the forceps channel in an endoscope, a manipulating wire extending through the sheath, and a pair of forceps cups provided at the distal end of the sheath that are driven to open and close by advancing and retracting the manipulating wire along the longitudinal axis. 
     To collect a tissue specimen, the forceps cups are closed but they might slip on the mucosal surface and fail to attain the intended result. To avoid this problem, some endoscopic biopsy forceps are provided with a needle that extends forward to project into the central part of a pair of forceps cups. 
     To collect a tissue specimen for biopsy with this type of endoscopic forceps, a pair of forceps cups are opened and the needle is pierced through the mucous membrane in the diseased part so as to fix the forceps cups in position; then, the manipulating wire is pulled toward the operator to close the forceps cups, whereupon a tissue specimen is collected within the pair of forceps cups. 
     A problem with this approach is that the needle pierced into the central part of the specimen can damage and deform the tissue of this vital part of the specimen to such an extent that the operator is unable to determine correctly if the diseased part is malignant or not. 
     SUMMARY OF THE INVENTION 
     An object, therefore, of the invention is to provide endoscopic biopsy forceps that allows a non-deformed, high-quality tissue specimen to be readily collected from the correct target position. 
     According to the invention, a needle or needles are provided that extend forward to project into and/or along a pair of forceps cups and this allows the tip portion of biopsy forceps to be positively secured on the mucosal membrane so that a tissue specimen of the diseased part can be easily detached from the correct target position and collected into the forceps cups. What is more, the needle or needles are offset from the center of the pair of forceps cups and this enables collection of a non-deformed, high-quality tissue specimen. 
     Endoscopic biopsy forceps preferably comprises a sheath, a manipulating wire extending through the sheath, a pair of forceps cups provided at the distal end of said sheath which are driven to open and close like beaks by advancing and retracting the manipulating wire along the longitudinal axis, and a needle that extends forward to project into and/or along said one pair of forceps cups, the needle being offset from the center of said one pair of forceps cups. 
     If desired, a plurality of needles may be positioned side by side and offset from the center of said one pair of forceps cups. 
     The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 11-106570 (filed on Apr. 14, 1999), which is expressly incorporated herein by reference in its entirety. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view showing in section the tip portion of endoscopic biopsy forceps according to a first embodiment of the invention; 
     FIG. 2 is a side view showing, with part taken away, the tip portion of the endoscopic biopsy forceps according to the first embodiment of the invention; 
     FIG. 3 is a side view showing the general construction of the endoscopic biopsy forceps according to the first embodiment of the invention; 
     FIG. 4 is a plan view showing in section the tip portion of endoscopic biopsy forceps according to a second embodiment of the invention; 
     FIG. 5 is a side view showing, with part taken away, the tip portion of the endoscopic biopsy forceps according to the second embodiment of the invention; and 
     FIG. 6 is a side view showing in section endoscopic biopsy forceps according to a third embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Embodiments of the invention are described below with reference to the accompanying drawings. 
     FIG. 3 shows endoscopic biopsy forceps according to a first embodiment of the invention. The forceps comprises a flexible sheath  1  to be inserted into or removed from the forceps channel in an endoscope (not shown) and a manipulating wire  2  that extends through the entire length of the flexible sheath  1  and which is free to advance and retract along the longitudinal axis. 
     A manipulating section  3  for controlling the manipulating wire  2  to either advance or retract is coupled to the basal end of the sheath  1  (which is the closer to the operator). An actuating tip  10  that can be driven with the manipulating wire  2  is coupled to the distal end of the sheath  1 . 
     FIGS. 1 and 2 show the actuating tip  10  in enlarged form. FIG. 2 is a side view with part taken away, and FIG. 1 is a plan view in partial section. The sheath  1  consists of a coil pipe  1   a  covered with a flexible tube  1   b ; the coil pipe  1   a  may be formed of a fine stainless steel wire that is wound in close turns in a specified diameter. If desired, either the coil pipe  1   a  or the flexible tube  1   b  may be omitted. 
     Coupled securely to the tip of the sheath  1  is a tip assembly  13  having a large slit  12  formed in the front portion. A support shaft  14  is mounted in the tip assembly  13  in such a way that it crosses the neighborhood of the distal end of the slit  12 . 
     A pair of forceps cups  11  are supported rotatably on the shaft  14  so that they can open and close like beaks by rotating about the shaft  14 . A known link mechanism  15  is provided within the slit  12  such that it is driven by the manipulating wire  2  to open and close the forceps cups  11 . 
     The link mechanism  15  is a pantograph consisting of four links joined pivotally in parallelogram form and the two front links are an integral part of the pair of forceps cups  11  so that they pivot on the support shaft  14 . 
     A driving rod  16  is coupled to the rear end of the link mechanism  15 . The distal end of the manipulating wire  2  is securely coupled to the driving rod  16  so that the link mechanism  15  can be actuated by remote control from the basal end of the sheath  1 . If the manipulating wire  2  is pushed forward, the pair of forceps cups  11  open as indicated by one-long-and-two-short dashed lines in FIG. 2; if the manipulating wire  2  is pulled toward the operator, the cups close as indicated by solid lines. 
     Two needles  20  extend forward from the distal end of the tip assembly  13  so that they project into the pair of forceps cups  11 . Each of the needles  20  is an integral projecting part of a mount seat  21  in thin plate form; the support shaft  14  is passed through the holes in the mount seats  21  so that they are in engagement with the tip assembly  13 . 
     A securing projection  21   a  erected at the rear end of each mount seat  21  is fitted into a hole made in each side wall of the tip assembly  13 ; as a result, the mount seats  21  are secured in position so that they will not rotate about the support shaft  14 . 
     As FIG. 2 shows, the two needles  20  lie in the same plane as the surface of engagement between the two forceps cups  11 . It should, however, be noted that both needles are offset from the longitudinal axis  50  through the center of the forceps cups  11  so that they are symmetrical with respect to said longitudinal axis. 
     To collect a tissue specimen for biopsy using the endoscopic biopsy forceps according to the first embodiment of the invention, the following procedure may be taken. First, the sheath  1  is passed through the treatment tool insertion channel in an endoscope (not shown) so that the actuating tip  10  is guided into a body cavity. A pair of forceps cups  11  are opened, the needles  20  are pierced through the mucous membrane of the diseased part so that the actuating tip  10  is fixed in position, and subsequently the manipulating wire  2  is pulled toward the operator to close the pair of forceps cups  11 . 
     The needles  20  pierced through the mucous membrane of the diseased part allow the actuating tip  10  to be positively secured on the mucosal surface so that a specimen of the diseased part can be easily detached from the right position and collected into the forceps cups  11 . 
     Since the needles  20  are not pierced in the central part of the tissue specimen but in positions offset from the center, the collected specimen is not deformed and by microscopic examination of it, the doctor can determine correctly if the diseased part is malignant or not. 
     The present invention is by no means limited to the foregoing embodiment and it may be applied to other techniques of biopsy, for example, “hot biopsy” in which a specimen for biopsy is collected with a radio-frequency current being applied to the forceps cups  11  via the manipulating wire  2 . 
     In the first embodiment, the needles  20  project into the forceps cups  11  but this is not the sole case of the invention. As shown in FIGS. 4 and 5 which show endoscopic biopsy forceps according to a second embodiment of the invention, the needles  20  may project along the peripheries of the forceps cups  11 . 
     In this case, relief grooves la must be formed in the forceps cups  11  to avoid interference with the needles  20 . Also note that the mount seats  21  in the second embodiment are formed to be larger than in the first embodiment. 
     FIG. 6 shows a third embodiment of the invention in which it is applied to so-called bipolar radio-frequency biopsy forceps. In this embodiment, two insulated conductor wires are used as manipulating wires  2 , each consisting of a lead wire  2   a  and an insulation coat  2   b.    
     A pair of forceps cups  11  are electrically insulated from each other and connected to different lead wires  2   a . Because of this arrangement, high-frequency cautery and coagulation can be performed with the two forceps cups  11  serving as a positive and a negative electrode in the absence of any counter electrode. 
     In the third embodiment, two needles  20  also extend forward from the distal end of the tip assembly  13  to project into the pair of forceps cups  11 . Again, the needles may be adapted to be movable along the peripheries of the forceps cups as in the second embodiment. 
     It should also be noted that the present invention is by no means limited to the three embodiments described above and various modifications may be made. For instances only one needle  20  may be used or, alternatively, three or more needles may be employed. All that is required is that the needle or needles should be offset from the center of the pair of forceps cups  11 .