Abstract: Embodiments of the invention relate to syringes that are adapted to make it easier for a user to aspirate fluids into the syringes. According to one embodiment, a syringe includes a plunger with a thumb rest at one end. One or more spacers extend from the thumb rest, and shelf that incorporates a distal thumb pushback surface may also be attached to the spacers. The relative configuration of the thumb rest, the spacers, and the shelf are such that a user may easily insert a thumb between the thumb rest and the shelf and may aspirate by raising the thumb above the thumb rest and pushing with the dorsal thumb against the pushback surface. Alternative embodiments of the invention may include an adapter configured to be attached to a plunger that lacks a dorsal thumb pushback surface, thereby allowing a user to conveniently use such a syringe for aspiration.