Disclosed is a bag including : a first envelope having at least one fill and/or discharge orifice for a biopharmaceutical fluid and a fill and/or discharge tube associated in a fluidtight manner with the fill and/or discharge orifice, a second envelope within which the first envelope is located, and a spacer element. The first envelope, the second envelope, and the spacer element form a coherent whole, in particular during use of the bag, and the fill and/or discharge tube traverses the second envelope by a fluidtight connection, the fill and/or discharge inlet being located outside the second envelope.