The catheter or cannula arrangement includes a catheter or cannula a sensing unit including a sensing element for sensing a flow of a fluid and an output unit operationally connectable to the sensing unit. The output unit is provided for receiving from the sensing unit signals related to the sensed flow of the fluid referred to as sensed signals, for obtaining, by processing the sensed signals, signals referred to as processed signals, and for outputting the processed signals, e.g., via a visual display. The output unit may include fixing structures attachment to tubing of the catheter or cannula. The sensing unit may be provided by a tube extension. The catheter or cannula may be a urinary catheter.
