An apparatus for treating a wall of a body cavity comprising an elongate probe member having a distal extremity with an outer surface and at least one recess opening onto the outer surface. When a suction source is coupled to the apparatus, a suction is created in the recess to draw a portion of the wall into the recess. A needle is slidably disposed in the elongate probe member and actuatable from outside the body for movement from a retracted position to an extended position in which the distal end portion of the needle extends into the recess whereby the needle can be extended into the portion of the wall drawn into the recess.