A biopsy device (10) and method are provided for obtaining a tissue sample, such as a breast tissue biopsy sample. The biopsy device includes a disposable probe assembly (14) with an outer cannula (30) having a distal piercing tip (38), a cutter lumen, and a cutter tube (40) that rotates and translates past a side aperture (34) in the outer cannula to sever a tissue sample. The biopsy device also includes a reusable hand piece (12) with an integral motor (172) and power source to make a convenient, untethered control for use with ultrasonic imaging. The reusable hand piece incorporates a probe oscillation mode to assist when inserting the distal piercing tip into tissue. A saline valve positioned by the reusable hand piece communicates a saline supply through the probe assembly to perform saline flush of the cutter tube and outer cannula.
