disclosed is an ergonomically improved hypodermic syringe which facilitates one - handed use by allowing the same hand that holds the syringe to operate the plunger conveniently to accomplish both the distal stroke and the proximal stroke . the syringe includes a pair of finger - stop structures on diametrically opposite sides of the barrel which block slippage in both proximal and distal directions and which do not occupy the barrel &# 39 ; s entire circumference and do not interfere with the legibility of a calibration scale that passes through the region of the barrel with which said structures are associated . a loop atop the syringe &# 39 ; s plunger member is also provided , which is adjustable to vary the size of the aperture thereof for a snug fit with fingers and thumbs of varying sizes . in combination , the adjustable loop and finger - stops make the syringe plunger easily operable in both directions with one hand . the result is a syringe which is inexpensive to manufacture , which is compact to store and ship , and which enables an aspiration maneuver , to test for the presence of blood indicating that a blood vessel has been penetrated , to be performed easily with one hand .