PROBLEM TO BE SOLVED: To provide a piping connection structure which, when a treatment is performed on an affected part in a body cavity while a fluid is recycled inside and outside the body cavity, can prevent air outside the body cavity from being kept supplied into the body cavity instead of the fluid.SOLUTION: The piping connection structure is for use in a system, which system includes: a recycling apparatus for recycling a fluid inside and outside a body cavity； a first pipe conduit forming a part of a first flow channel for the fluid supplied into the body cavity； a second pipe conduit forming a part of a second flow channel for the fluid sucked from inside the body cavity； a first piping material connected to the first pipe conduit outside the body cavity and forming the other part of the first flow channel； and a second piping material connected to the second pipe conduit outside the body cavity and forming the other part of the second flow channel. The connection between the first pipe conduit and the first piping material is always released prior to the connection between the second pipe conduit and the second piping material, and the first flow channel is shut off when the connection between the first pipe conduit and the first piping material is released.SELECTED DRAWING: Figure 2【課題】体腔内外で流体を還流させつつ体腔内の患部の処置を行う際に、体腔外の空気が当該流体の代わりに体腔内へ供給され続けてしまうことを防止可能な配管接続構造を提供する。【解決手段】配管接続構造は、体腔内外で流体を還流させる還流装置と、体腔内へ供給される流体の第１の流路の一部分を形成する第１の管路と、体腔内から吸引される流体の第２の流路の一部分を形成する第２の管路と、体腔外において第１の管路に接続され、第１の流路の他の部分を形成する第１の配管部材と、体腔外において第２の管路に接続され、第２の流路の他の部分を形成する第２の配管部材と、を有するシステムにおける配管接続構造であって、第１の管路と第１の配管部材との接続が、第２の管路と第２の配管部材との接続よりも常に先に解除され、第１の管路と第１の配管部材との接続が解除されている場合に第１の流路が遮断される。【選択図】図２
