A device and method to diagnose an internal abnormality in a living subject by sensing a passively occurring electromagnetic radiation signal associated with the abnormality and inside an orifice of the subject. Diagnosis includes detection, imaging or identification of the abnormality. An instrument is used either to bring a sensor into the orifice or to transmit the signal to a sensor located outside of the orifice. An example of the instrument includes a prior art endoscope.