An access disconnection system includes: a material capable of absorbing blood from a patient upon an arterial or venous line disconnection； a light emitter positioned to emit light onto the material； a light receiver positioned to receive light reflected off of the material； and electronic circuitry operably coupled to at least one of the light emitter and receiver, the circuitry configured to provide an output (i) when light received by the receiver reaches a particular level or (ii) indicative of an amount of light received by the light receiver.
