Non-seeding biopsy device and method
Tissue biopsy is performed through a central passage of a cannula covered with a protective sleeve. The protective sleeve is attached at one end to a location at or near a distal end of the cannula. After the biopsy procedure is completed, the cannula is withdrawn so that its exterior slides through the sleeve. In this way, the trailing edge of the sleeve is invaginated within the proximal portions of the itself to envelop the sleeve exterior and reduce the risk of inadvertent tumor cell seeding.
1. A method for obtaining a sample from solid tissue, said method comprising:
accessing a site in the solid tissue by advancing a cannula covered with a protective sleeve through the solid tissue, wherein advancement of the cannula creates a tissue tract;
obtaining the sample through a central passage of the cannula, wherein obtaining the sample comprises advancing a stylet from the cannula to capture sample in a recess on the stylet and advancing the cannula to excise the captured sample; and
withdrawing the cannula, wherein a distal region of the cannula is fixedly attached to a distal portion of the sleeve so that the distal portion of the sleeve is pulled by the cannula to inwardly evert as the cannula is withdrawn, through the tissue tract.
2. A method as in claim 1 , wherein a sliding friction between the sleeve and the cannula is less than a sliding friction between the sleeve and the tissue so that axial sliding of the sleeve in the tissue is inhibited.
3. A method as in claim 1 , wherein accessing comprises advancing the cannula with the stylet positioned in the central passage, wherein the stylet has a sharpened tip which extends distally beyond a distal end of the cannula.
4. A method as in claim 1 , wherein accessing comprises:
positioning the protective sleeve in a furled configuration at a percutaneous access site on a tissue surface; and
advancing the cannula through the access site to unfurl the sleeve and cover the cannula as the cannula is advanced.
5. A method as in claim 4 , wherein advancing the cannula through the access site comprises capturing a free end of the protective sleeve, wherein the captured end is pulled by the cannula.
6. A method for obtaining a sample from solid tissue, said method comprising:
accessing a site in the solid tissue by advancing a cannula covered with a protective sleeve through the solid tissue, wherein the cannula has a central passage with a stylet positioned therein with a sharpened tip which extends distally beyond a distal end of the cannula to create a tissue tract while the cannula is advanced;
obtaining the sample through a central passage of the cannula by advancing the stylet from the cannula to capture sample in a recess on the stylet and advancing the cannula to excuse the captured sample; and
withdrawing the cannula through the protective sleeve, wherein a sliding friction between the sleeve and the cannula is less than a sliding friction between the sleeve and the tissue tract so that axial sliding of the sleeve in the tissue is inhibited.
7. A method as in claim 6 , wherein a distal region of the cannula is fixedly attached to a distal portion of the sleeve so that the distal portion of the sleeve is pulled by the cannula to inwardly evert as the catheter is withdrawn.
8. A method as in claim 6 , wherein accessing comprises positioning the protective sleeve in a furled configuration at a percutaneous access site on a tissue surface; and
advancing the cannula through the access site to unfurl the sleeve and cover the cannula as the cannula is advanced.
9. A method as in claim 8 , advancing the cannula through the access site comprises capturing a free end of the protective sleeve, wherein the captured end is pulled by the cannula.