A method for puncturing a proximal membrane without puncturing a second, distal membrane is provided. The method comprises distally advancing an elongated body through an elongated tubular member to a first position where a distal end of the elongated body is in a first configuration. In the first configuration, the distal end of the elongated body is positioned outside the distal end of the elongated tubular member. The distal end of the elongated body has a distal tip, in this first configuration, that is sufficiently rigid and sharp to puncture the first, proximal membrane. From this first configuration, the distal tip of the elongated body is slightly advanced puncture the first, proximal membrane. After puncturing the first, proximal membrane, the elongated body is advanced through the punctured proximal membrane whereby the distal tip of the elongated body moves into a second configuration. In the second configuration, the distal tip of the elongated body curves into a j-shape, forming a blunt distal surface facing the second, distal membrane.