Apparatus and method for detecting connectivity in a channel in an endoscope undergoing reprocessing using an automatic reprocessor, the apparatus including a source of pressurized fluid which may be a gas alone or gas and liquid and a back pressure detector connected to the channel or channels of interest in the endoscope, the method including providing a source of pressurized fluid, directing the pressurized fluid to a channel in an endoscope, monitoring the time for the back pressure in the pressurized fluid to decay to a predetermined level; and determining whether the channel is connected and open or disconnected by comparing the decay time of the actual back pressure to one or more predetermined values corresponding to the specific channel or channels and model of endoscope undergoing reprocessing.