A device for detection of internal bleeding in a patient's body, the device comprising: an IR light source configured to generate light in the Infra-Red spectral range; an IR light detector configured to detect light in the Infra-Red spectral range; an optical interface comprising: one or more delivery component, comprising at least one first optical channel, and configured to deliver IR light generated by said IR light source and to transmit said IR light through an at least one respective first sub-area, on an area of a skin of said patient, into an internal layer of the body, and one or more collection component, comprising at least one second optical channel, configured to collect IR light from an at least one respective second sub-area, on said area of said skin, and deliver said collected IR light to said IR light detector a reference signal source configured to generate a Radio-Frequency reference signal at a frequency above about 0.5MHz; wherein the device further comprises: a reference signal detector configured to detect said reference signal; a reference signal interface comprising a transmitting RF antenna (252, 1052) for delivering the reference signal through the skin into the internal layer, and a receiving RF antenna configured for collecting the reference signal (254, 1054), or the reference signal interface comprising a single RF antenna for delivering the reference signal wherein an IR light detected by said IR detector has a wavelength λ1 and a reference signal detected by said reference signal detector has a wavelength λ2 substantially different from λ1, through the skin into the internal layer and for collecting the reference signal, and a signal processing module comprising a processor configured to compare measurement results of detected IR light, detected by said IR detector, and measurement results of detected reference signal, detected by said reference signal detector, thereby detecting an internal bleeding in a patient's body. an IR light source configured to generate light in the Infra-Red spectral range; an IR light detector configured to detect light in the Infra-Red spectral range; an optical interface comprising: one or more delivery component, comprising at least one first optical channel, and configured to deliver IR light generated by said IR light source and to transmit said IR light through an at least one respective first sub-area, on an area of a skin of said patient, into an internal layer of the body, and one or more collection component, comprising at least one second optical channel, configured to collect IR light from an at least one respective second sub-area, on said area of said skin, and deliver said collected IR light to said IR light detector one or more delivery component, comprising at least one first optical channel, and configured to deliver IR light generated by said IR light source and to transmit said IR light through an at least one respective first sub-area, on an area of a skin of said patient, into an internal layer of the body, and one or more collection component, comprising at least one second optical channel, configured to collect IR light from an at least one respective second sub-area, on said area of said skin, and deliver said collected IR light to said IR light detector a reference signal source configured to generate a Radio-Frequency reference signal at a frequency above about 0.5MHz; wherein the device further comprises: a reference signal detector configured to detect said reference signal; a reference signal interface comprising a transmitting RF antenna (252, 1052) for delivering the reference signal through the skin into the internal layer, and a receiving RF antenna configured for collecting the reference signal (254, 1054), or the reference signal interface comprising a single RF antenna for delivering the reference signal a reference signal detector configured to detect said reference signal; a reference signal interface comprising a transmitting RF antenna (252, 1052) for delivering the reference signal through the skin into the internal layer, and a receiving RF antenna configured for collecting the reference signal (254, 1054), or the reference signal interface comprising a single RF antenna for delivering the reference signal wherein an IR light detected by said IR detector has a wavelength λ1 and a reference signal detected by said reference signal detector has a wavelength λ2 substantially different from λ1, through the skin into the internal layer and for collecting the reference signal, and a signal processing module comprising a processor configured to compare measurement results of detected IR light, detected by said IR detector, and measurement results of detected reference signal, detected by said reference signal detector, thereby detecting an internal bleeding in a patient's body.