An EIT system (1) adapted to detect internal bleeding in a body portion, the EIT system (1) comprising a plurality of electrodes (3) adapted in use to extend in a substantially linear orientation across one side only of the body portion and to be applied in electrical contact with the skin of the body portion, a current source adapted to cyclically apply an electric current between one pair of the electrodes (3), a voltage measuring means to measure the voltage across each of the other pairs of the electrodes resulting from the current, a data collection system (2) and a data analysis system (4) to analyze data resulting from the voltages that are measured by the voltage measuring means, wherein the analysis system (4) is configured to obtain quantitative information related to amounts and rates of conductive tissue changes occurring in the body, based on an EIT analysis equivalent to that obtained from data derived from electrodes spaced around the full perimeter of the body portion. Also disclosed is an electrode belt suitable for bioelectrical use and in particular for detection of change of volume of tissue in a body portion.