Abstract: A method and apparatus for washing the bladder of a patient with an indwelling catheter. The method comprises introducing the tip of a prefilled bladder washing device into the catheter, expelling the liquid from the device to the bladder, latching the device in its compressed position, maintaining the liquid in the bladder a predetermined amount of time and then unlatching the device, withdrawing the previously introduced liquid thereinto, and disposing of the device. Asepsis is assured by the present method. The apparatus has guiding and expansion and contraction means associated therewith as well as latching means that do not interfere with the operation of the device yet assures secure latching in the compressed position.