An implantable medical device configured to monitor fluid in proximity to an implantable medical device for an inadvertent introduction of infusate into a pocket of tissue surrounding the implantable medical device during a refill procedure, the implantable medical device including a refillable infusate delivery system, the refillable infusate delivery system including a reservoir in fluid communication with an access port, and a conductivity sensor configured to monitor fluid in proximity to the conductivity sensor for an introduction of infusate into a pocket of tissue surrounding the implantable medical device, wherein the conductivity sensor comprises a pair of electrodes positioned on an external surface of the implantable medical device.