Residual Soil Detection (weekly, quarterly & yearly) uses an endoscope that has been soiled in use. The endoscope is processed through a w/d cycle and tested by the ninhydrin method for the presence of soil.
Due to the delicate nature of endoscopes the use of a surrogate device designed to simulate an endoscope in use may be preferred. The surrogated device can be soiled using the appropriate anaesthetic and endoscope soil, inside and outside the device. The soil is dried for half an hour to 2 hours before use. After processing there should be not residual soil remaining inside or surface of the endoscope. For the quarterly and annual tests the w/d basin of the machine can be soiled and tested for residual material after processing.

Channel Patency Test (quarterly) is a test to determine if the w/d machine can detect a partial blockage of each endoscope channel. The suggested test device in HTM2030 is 100 mm long 0.5 mm ID glass tube attached to the test channel. The use of fragile glass tube in an endoscope w/d is unwise. Hypodermic syringe needles with the cover in place can be substituted.