Abstract: An operable syringe assembly includes a barrel having a chamber for retaining fluid. A proximal end of the barrel includes an aperture therethrough. A distal end of the barrel includes a passageway therethrough communicating with the chamber. A stopper is slidably positioned in fluid-tight engagement inside the barrel. A plunger rod, having an elongate body portion, engages the stopper to facilitate operation of the stopper. The body portion of the plunger rod extends outwardly from the proximal end of the barrel, through the aperture. A flexible cover is attached to the barrel covering the aperture and containing that portion of the body portion of the plunger rod protruding from the aperture. The cover is flexible enough and strong enough to allow movement of the plunger rod for operating the syringe without tearing. The cover acts as a barrier for helping to block the transfer of fluid and particulate matter between the chamber and the environment.