An access site disconnection system and method are disclosed. Radio frequency transmitters and receivers are placed near an access site. When a patient receives dialysis treatment, wetness may arise from blood if the access needle becomes disconnected from the access site. Radio-frequency transmitters are mounted on or near gauze or other absorbent material placed adjacent the access site, as are radio-frequency receivers. After the sensors are placed, the dialysis machine and radio-frequency control circuit may be initialized or baselined, and dialysis treatment, such as hemodialysis, begun. If blood leaks from the access site, such as if the access needle is dislodged, the blood attenuates the radio frequency transmissions, which are detected by the receivers. A signal is sent to a controller or to an output device to raise an alert or sound an alarm.