Safety insert (20) for an extracorporeal circuit (22), comprising: - a first half shell (24) comprising a first tubular connector (26) comprising a base (28) having a substantially cylindrical shape and defining a X axis； - a second half housing (34) comprising a second tubular connector (36) designed for connection to a transducer (21)； - a hydrophobic semipermeable membrane (38) enclosed between the first half shell (24) and the second half shell (34)； wherein the base (28) is designed to receive one end (42) of a branching tube (40) from the extracorporeal circuit (22), said end (42) defining a front surface substantially in the form of a ring (44) and which is capable of being inserted into the base (28) in an axial direction along the X axis； and wherein the base (28) comprises: one or more stops (30) designed to form a support for the front end surface (42) such that they define a limit stop in the axial direction for the end (42) ； said stops (30) defining a partial support for said ring (44) of the front end surface (42) in order to define at least one radially outer cavity (32) designed to leave at least one radially outer area of the ring (44) without support, characterized in that the base (20) comprises a plurality of stops (30) extending in a substantially radial direction, said stops (30) that are tangentially spaced from each other.Inserto (20) de seguridad para un circuito (22) extracorpóreo, que comprende: - una primera semicarcasa (24) que comprende un primer conector (26) tubular que comprende una base (28) que tiene una forma sustancialmente cilíndrica y que define un eje X； - una segunda semicarcasa (34) que comprende un segundo conector (36) tubular diseñado para la conexión a un transductor (21)； - una membrana (38) semipermeable hidrófoba encerrada entre la primera semicarcasa (24) y la segunda semicarcasa (34)； en la que la base (28) está diseñada para recibir un extremo (42) de un tubo (40) de ramificación desde el circuito (22) extracorpór
