Patent ID: 8167818

Claim:
A method of relieving vacuum in a biopsy apparatus that comprises a first cannula defining a first lumen therethrough and a tissue-receiving opening in communication with the first lumen; a second cannula slidably disposed in the first lumen, wherein the second cannula defines a second lumen therethrough, and a vacuum source in fluid communication with the second lumen, the method comprising: applying vacuum from the vacuum source through at least one motor to the second lumen; providing an open leak path through an engagement area between a first cannula mounting hub and a housing that permits fluid communication between the first lumen and the atmosphere, the leak path is continuously open and fluid is drawn from the leak path and through the first cannula; retracting the second cannula to permit tissue to prolapse into the tissue receiving opening due to the vacuum created through the second lumen; translating the second cannula toward the distal end of the first cannula to sever the tissue that has prolapsed into the tissue receiving opening; aspirating the severed tissue through the second lumen; and selectively relieving vacuum distally of the severed and aspirating tissue by retracting the second cannula away from the distal end of the first cannula thereby permitting the second lumen to communicate with the first lumen and the leak path while a portion of the biopsy apparatus, including the tissue receiving opening, is positioned within tissue.