Method for operating a biopsy apparatus

A method for operating a biopsy apparatus includes providing a cannula having a lumen, a proximal portion, a closed distal end, and an orifice located on a circumferential surface of the cannula, the orifice being configured to receive a tissue sample into the lumen of the cannula; providing a cutting sheath coaxially disposed with the cannula, the cutting sheath being configured to be movable relative to the cannula to selectively cover the orifice; providing a pressure chamber coupled to the proximal portion of the cannula, the pressure chamber configured to contain a pressure; providing a bifurcated valve assembly interposed between the cannula and the pressure chamber, the bifurcated valve assembly having a first valve and a second valve; operating the first valve to release the pressure into the lumen of the cannula; and operating the second valve to facilitate an inflow of air into the pressure chamber.