A disposable syringe and a push rod (3) for use in the disposable syringe. The push rod (3) comprises a proximal end (11), a distal end (10) and an axis (12) extending through the proximal end (11) and the distal end (10). The distal end (10) of the push rod (3) is provided with a snap-fitting mechanism (14) and a stop flange (13) located at a proximal side of the snap-fitting mechanism (14). The stop flange (13) comprises a main body portion (15) formed about the axis (12) of the push rod (3) and a plurality of finger portions extending from the main body portion (15) in a direction away from the axis (12) of the push rod (3). A smaller push force continues to be applied to the push rod (3) upon completion of injection, thereby achieving an additional stroke needed when the distal end (10) of the push rod (3) snap-fits with a needle seat (2) and lessening patient's pains.
