Medical appliance comprises a color camera (17) connected to a recognition device for recognizing the color of blood and the size of the recorded image surface. An independent claim is also included for a method for monitoring the operation of the above medical appliance. Preferred Features: The camera is a digital camera with devices for determining the number of pixels which are exposed by the color of the blood. A transformation device transforms the signals released in the color chamber into a further color chamber. A memory device stores criteria for blood recognition.
