Apparatus for detecting presence of a blood sample is presented where the apparatus comprises a housing having an aperture, the aperture configured to receive a body part of a user, a camera having a field of view that encompasses at least a portion of the aperture, the camera configured to capture images of the users body part, and a processor. The processor is configured to control operation of the camera receive the captured images, and determine whether a predetermined quantity of blood is present on the surface of the users body part.