A urine flow detection system for detecting urine flowing from the bladder to the kidney(s) and / or ureter(s) in a subject using electrical impedance tomography technology, the system comprising: an impedance measurement module comprising a plurality of electrodes, respective ones of the electrodes being adapted, when in use, to be positioned on the subject's body surface adjacent to one of a bladder, ureter(s) or kidney(s) of the subject and configured to record impedance measurements in the kidney(s) and/or ureter(s) wherein the impedance changes are operably detected by electrical impedance, and a processor configured to receive data from the impedance measurement module the data being impedance measurements taken over a period of time, wherein the processor is configured to analyse the measurements to create a series of impedance distribution images or graphs, which each correspond to the volume of liquid flowing to the kidneys at a particular time point, wherein the measurements are taken continuously as bladder pressure increases during micturition or filling, or as bladder pressure increases as pressure is applied to the abdomen and hence to the bladder, either manually or by the system itself, wherein the processor is configured to gather and process the impedance distribution images to output an average impedance distribution image or graph and the processor is further configured to analyse the differences between measurements or groups of measurements to provide an indication of volume changes in the kidney resultant from pressure increases in the bladder, the processor being configured to compare indicated volume changes of the average impedance distribution image or graph to a base-line image or graph obtained before or after urination to provide an indication of the presence or absence of vesicoureteral reflux, VUR, in the subject. an impedance measurement module comprising a plurality of electrodes, respective ones of the electrodes being adapted, when in use, to be positioned on the subject's body surface adjacent to one of a bladder, ureter(s) or kidney(s) of the subject and configured to record impedance measurements in the kidney(s) and/or ureter(s) wherein the impedance changes are operably detected by electrical impedance, and a processor configured to receive data from the impedance measurement module the data being impedance measurements taken over a period of time, wherein the processor is configured to analyse the measurements to create a series of impedance distribution images or graphs, which each correspond to the volume of liquid flowing to the kidneys at a particular time point, wherein the measurements are taken continuously as bladder pressure increases during micturition or filling, or as bladder pressure increases as pressure is applied to the abdomen and hence to the bladder, either manually or by the system itself, wherein the processor is configured to gather and process the impedance distribution images to output an average impedance distribution image or graph and the processor is further configured to analyse the differences between measurements or groups of measurements to provide an indication of volume changes in the kidney resultant from pressure increases in the bladder, the processor being configured to compare indicated volume changes of the average impedance distribution image or graph to a base-line image or graph obtained before or after urination to provide an indication of the presence or absence of vesicoureteral reflux, VUR, in the subject.